playground: Allow specifying port offset

[breezewish]

What problem does this PR solve?

What is changed and how it works?

Sometimes we want to start multiple clusters concurrently (and also preserve them).

Preserving data is possible by specifying --tag.

But multiple co-exist clusters will meet issues after restart because dynamic port may be changed and stores are regarded as new stores.

This PR adds --port-offset so that this could work nicely, e.g:

• Cluster1: --tag=cluster1 --port-offset=10000
• Cluster2: --tag=cluster2 --port-offset=20000

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Code changes

• Has exported function/method change
• Has exported variable/fields change
• Has interface methods change
• Has persistent data change

Side effects

• Possible performance regression
• Increased code complexity
• Breaking backward compatibility

Related changes

• Need to cherry-pick to the release branch
• Need to update the documentation

Release notes:

NONE

[ti-chi-bot]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-08-20 05:34:21.741570159 +0000 UTC m=+243656.876020281: ☑️ agreed by xhebox.