Enhance perf test

[qiuming-best]

Thank you for contributing to Velero!

Please add a summary of your change

• Make Velero pod request configurable in E2E
• Add timestamp In metrics
• Increase the backup timeout time

Does your change fix a particular issue?

Fixes #(issue)

Please indicate you've done the following:

• Accepted the DCO. Commits without the DCO will delay acceptance.
• Created a changelog file or added /kind changelog-not-required as a comment on this pull request.
• Updated the corresponding documentation in site/content/docs/main.

[codecov]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (6b7ce66) 61.02% compared to head (507157f) 61.69%.
Report is 62 commits behind head on main.

Files	Patch %	Lines
pkg/install/deployment.go	57.14%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7090      +/-   ##
==========================================
+ Coverage   61.02%   61.69%   +0.67%     
==========================================
  Files         255      258       +3     
  Lines       27040    27644     +604     
==========================================
+ Hits        16500    17055     +555     
- Misses       9361     9395      +34     
- Partials     1179     1194      +15     

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