release-23.2: roachtest: assign adminui ports dynamically for virtual clusters

[blathers-crl]

Backport 2/2 commits from #117505 on behalf of @DarrylWong.

/cc @cockroachdb/release

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This was originally removed in #115599 due to #114097 merging, but adminui was reverted in #117141 and mistakenly did not revert the special case for virtual clusters. We unskip the multitenant/distsql tests as well.

Release note: None
Fixes: #117150
Fixes: #117149
Epic: None

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Release justification: test-only change.

[blathers-crl]

Thanks for opening a backport.

Please check the backport criteria before merging:

• Backports should only be created for serious
  issues or test-only changes.
• Backports should not break backwards-compatibility.
• Backports should change as little code as possible.
• Backports should not change on-disk formats or node communication protocols.
• Backports should not add new functionality (except as defined
  here).
• Backports must not add, edit, or otherwise modify cluster versions; or add version gates.
• All backports must be reviewed by the owning areas TL and one additional
  TL. For more information as to how that review should be conducted, please consult the backport
  policy.

If your backport adds new functionality, please ensure that the following additional criteria are satisfied:

• There is a high priority need for the functionality that cannot wait until the next release and is difficult to address in another way.
• The new functionality is additive-only and only runs for clusters which have specifically “opted in” to it (e.g. by a cluster setting).
• New code is protected by a conditional check that is trivial to verify and ensures that it only runs for opt-in clusters. State changes must be further protected such that nodes running old binaries will not be negatively impacted by the new state (with a mixed version test added).
• The PM and TL on the team that owns the changed code have signed off that the change obeys the above rules.
• Your backport must be accompanied by a post to the appropriate Slack
  channel (#db-backports-point-releases or #db-backports-XX-X-release) for awareness and discussion.

Also, please add a brief release justification to the body of your PR to justify this
backport.

[cockroach-teamcity]

This change is 

[DarrylWong]

#114097 hasn't been backported yet so I think we need to set sqlport to 0 as well (I can get to this soon, just mentioning)

[yuzefovich]

Thanks. I see that we backported #116525 yesterday, so we got failures today on 23.2 branch. I'll defer to you Darryl on what needs to be done to fix those.

[DarrylWong]

Added startOpts.RoachprodOpts.SQLPort = 0 and confirmed multitenant/distsql tests pass on gceworker