Change typo 'waitting' to 'waiting' in output messages within pdapi.go.

[guangleibao]

What problem does this PR solve?

Correct typo in pdapi messages.

What is changed and how it works?

Change the string from 'waitting' to 'waiting'. There are 6 'waiiting' typos in pdapi.go:

pkg/cluster/api/pdapi.go:288:           pc.l().Debugf("Still waitting for the PD leader to be elected")
pkg/cluster/api/pdapi.go:289:           return perrs.New("still waitting for the PD leader to be elected")
pkg/cluster/api/pdapi.go:447:           pc.l().Debugf("Still waitting for the PD leader to transfer")
pkg/cluster/api/pdapi.go:448:           return perrs.New("still waitting for the PD leader to transfer")
pkg/cluster/api/pdapi.go:527:                   "\t  Still waitting for %d store leaders to transfer...",
pkg/cluster/api/pdapi.go:735:                           return perrs.New("still waitting for the PD node to be deleted")

[CLAassistant]

All committers have signed the CLA.

[codecov-commenter]

Codecov Report

Attention: 5 lines in your changes are missing coverage. Please review.

Comparison is base (ced2d6d) 47.65% compared to head (1eefbee) 52.47%.

:exclamation: Current head 1eefbee differs from pull request most recent head fb1af3a. Consider uploading reports for the commit fb1af3a to get more accurate results

Files	Patch %	Lines
pkg/cluster/api/pdapi.go	16.67%	5 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #2330 +/- ## ========================================== + Coverage 47.65% 52.47% +4.81% ========================================== Files 307 325 +18 Lines 33819 34764 +945 ========================================== + Hits 16116 18240 +2124 + Misses 15715 14319 -1396 - Partials 1988 2205 +217 ``` | [Flag](https://app.codecov.io/gh/pingcap/tiup/pull/2330/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pingcap) | Coverage Δ | | |---|---|---| | [cluster](https://app.codecov.io/gh/pingcap/tiup/pull/2330/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pingcap) | `39.19% <16.67%> (-2.76%)` | :arrow_down: | | [dm](https://app.codecov.io/gh/pingcap/tiup/pull/2330/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pingcap) | `25.55% <0.00%> (?)` | | | [playground](https://app.codecov.io/gh/pingcap/tiup/pull/2330/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pingcap) | `15.25% <0.00%> (?)` | | | [tiup](https://app.codecov.io/gh/pingcap/tiup/pull/2330/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pingcap) | `33.48% <ø> (ø)` | | | [unittest](https://app.codecov.io/gh/pingcap/tiup/pull/2330/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pingcap) | `22.29% <0.00%> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pingcap#carryforward-flags-in-the-pull-request-comment) to find out more.

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[kaaaaaaang]

/lgtm

[kaaaaaaang]

/approve

[ti-chi-bot[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: kaaaaaaang

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Needs approval from an approver in each of these files: - ~~[OWNERS](https://github.com/pingcap/tiup/blob/master/OWNERS)~~ [kaaaaaaang] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment

[breezewish]

@guangleibao Please sign the CLA agreement to get PR merged. Thanks a lot!

[ti-chi-bot[bot]]

[LGTM Timeline notifier]

Timeline:

• 2023-12-14 10:44:11.117280446 +0000 UTC m=+525742.154507370: :ballot_box_with_check: agreed by kaaaaaaang.
• 2023-12-18 08:56:02.042308669 +0000 UTC m=+864853.079535596: :heavy_multiplication_x::repeat: reset by ti-chi-bot[bot].
• 2023-12-19 06:10:55.182456332 +0000 UTC m=+941346.219683258: :ballot_box_with_check: agreed by breezewish.
• 2023-12-19 09:44:06.277219853 +0000 UTC m=+954137.314446782: :heavy_multiplication_x::repeat: reset by ti-chi-bot[bot].

[ti-chi-bot[bot]]

New changes are detected. LGTM label has been removed.

[guangleibao]

TiUP CLA agreement signed.

[breezewish]

Thanks for your contribution!