Clean up old SDK/VmService checks

[liamappelbe]

We have a bunch of version checks for the VmService version, and a bunch of checks that are skipped for old SDKs. Some of these are very old, and can be cleaned up since we've bumped the minimum SDK version. Figure out the VmService version associated with our min SDK version, and then remove all these old checks.

[Victowolf]

@liamappelbe
Since we've already bumped the minimum SDK version, we can clean up the outdated VmService version checks. The next step would be to determine the VmService version corresponding to our current minimum SDK version and remove any redundant conditionals.

I'll look into this and try to update the code accordingly.

[Victowolf]

@liamappelbe
I reviewed the codebase and searched for version checks related to VmService and old SDKs, but I didn’t find any remaining outdated checks that need cleanup. It’s possible that these were already removed in a previous update when the minimum SDK version was bumped to 3.4.0 (with VmService version 15.0.0).

To confirm, I also checked the commit history, but I didn’t see any direct references to old version checks. If there's a specific instance that was flagged before, let me know, and I will take another look!

[liamappelbe]

I removed them in this PR: dart-archive/coverage#502. I just forgot to close this issue