Fix build issues

[shanth96]

This PR is a followup to #149 in order to fix build-specific issues.

Essentially, vttestserver builds were failing with the error:

#10 93.94 The following packages have unmet dependencies:
#10 94.01  percona-xtrabackup-80 : Depends: libprocps7 (>= 2:3.3.15-1) but it is not installable
#10 94.02 E: Unable to correct problems, you have held broken packages.

This is because they updated vttestserver Dockerfile to use bullseye image in vitessio#13921 but try to install packages for buster inside install_dependencies.sh.

This PR adds another "flavor" to the install_dependencies.sh script to use bullseye repo and install the correct packages that would work with bullseye.

[brendar]

1. Is this impacting upstream as well?
2. Would it make sense to update the package references rather than introduce a new "flavor" which generally refers to the mysql version/distribution and not the OS?

[pawandubey]

1. Is this impacting upstream as well?

This is fixed in upstream version 18 onwards as that is when they changed the repositories to bullseye for everything except mysql 5.7, but does impact versions 16 and 17 as far as we can tell.

2. Would it make sense to update the package references rather than introduce a new "flavor" which generally refers to the mysql version/distribution and not the OS?

We discussed this with Austen earlier today and decided to backport the upstream changes that fix the issue in later releases into our releases for 16 and 17. Shanth can expand more. This is the main PR to bring in I think: vitessio#13664

[shanth96]

We discussed this with Austen earlier today and decided to backport the upstream changes that fix the issue in later releases into our releases for 16 and 17. Shanth can expand more. This is the main PR to bring in I think: vitessio#13664

Yes, we're gonna try to bring in the upstream PR and if it fixes our issue, we'll cherry pick that onto v16.

The original intention of this PR was as a stop-gap solution till we upgraded to v18. Since we will be upgrading things consecutively, we thought it might be okay to fix it like this temporarily without upstreaming a proper fix.

[shanth96]

Closing in favor of #153