Remove request trial form from docs

[khanhtc1202]

What this PR does / why we need it:

Remove trial form link from docs, we want users to use the tutorial instead.

Which issue(s) this PR fixes:

Fixes #

Does this PR introduce a user-facing change?:

• How are users affected by this change:
• Is this breaking change:
• How to migrate (if breaking change):

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 22.80%. Comparing base (c9861c7) to head (7331de0).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #5145 +/- ## ======================================= Coverage 22.80% 22.80% ======================================= Files 412 412 Lines 43827 43827 ======================================= Hits 9996 9996 Misses 33044 33044 Partials 787 787 ```

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