Add jemalloc memory profiling (part 1)

[JaySon-Huang]

What problem does this PR solve?

Issue Number: related to #3236

Problem Summary: Add options for building TiFlash with jemalloc memory profiling enabled.

What is changed and how it works?

• Add ENABLE_JEMALLOC_PROF for building TiFlash with jemalloc memory profiling enabled, but set it to false by default (This PR can not resolve the issue that TiFlash get stuck occasionally when mem-profiling is enabled && actived)
• Add a "Welcome to TiFlash" when starting TiFlash, keep same behavior as TiKV/TiDB/PD
• Add a "Enable Features: " message for TiFlash version info

Related changes

• PR to update pingcap/docs/pingcap/docs-cn:
• Need to cherry-pick to the release branch:

Check List

Tests

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

Side effects

Release note

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• solotzg

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[JaySon-Huang]

/merge

[ti-chi-bot]

@JaySon-Huang: It seems you want to merge this PR, I will help you trigger all the tests:

/run-all-tests

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[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 8bab7c4