Update tilt ubuntu image to avoid glibc error

[anshulahuja98]

Thank you for contributing to Velero!

Please add a summary of your change

Ubuntu: focal operates on slightly older versions. It has glibc version 2.31 as compared to newer OS use 2.35.

This leads to issues in the pod coming up, the pod keeps crashing with error message cribbing that the appropriate glibc version was not found.

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.

[anshulahuja98]

/kind changelog-not-required

[codecov-commenter]

Codecov Report

Merging #6430 (cc76bc0) into main (de83980) will increase coverage by 0.76%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #6430      +/-   ##
==========================================
+ Coverage   58.41%   59.18%   +0.76%     
==========================================
  Files         227      229       +2     
  Lines       23771    24193     +422     
==========================================
+ Hits        13887    14319     +432     
+ Misses       8899     8875      -24     
- Partials      985      999      +14     

see 15 files with indirect coverage changes

[anshulahuja98]

Squashed commit and fixed DCO, addressed PR comment.
Ready to check- in

[anshulahuja98]

@ywk253100 can you pl review/ approve this.