ebs br: print out the elapsed time for each snapshot size calculation (#5263)

[ti-chi-bot]

This is an automated cherry-pick of #5263

What problem does this PR solve?

Closes #5264

What is changed and how does it work?

This pr will directly print the elapsed time of snapshot size calculation in backup pod log.

Code changes

• Has Go code change
• Has CI related scripts change

Tests

• Unit test
• E2E test
• Manual test
• No code

Side effects

• Breaking backward compatibility
• Other side effects:

Related changes

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

Release Notes

Please refer to Release Notes Language Style Guide before writing the release note.

[ti-chi-bot]

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