Migration: Jenkins -> Semaphore

[cprovencher]

Action required after merging

If these changes should be on older .x branches as well, apply them to the oldest .x branch, then pint merge them all the way up to master. Then you can close this PR.

Ticket

https://confluentinc.atlassian.net/browse/CPKAFKA-9986

Changes

1) Deletes the Jenkinsfile. 2) Adds the service-bot config (service.yml) and semaphore files generated by service-bot

Why are we migrating?

Read the background and motivation
Please merge this PR ASAP because we plan on shutting down Jenkins by the end of the year.

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[arihant-confluent]

@cprovencher, we need to apply this change to the oldest branch in use. That could be 6.0.x

[jkao97]

Believe it's 6.1.x. Can we first apply to master and then backport?

[cprovencher]

I opened the PR against 6.1.x https://github.com/confluentinc/common/pull/585