Unload MsQuic after checking for QUIC support to free resources

[wfurt]

Fixes #74629

This PR unloads MsQuic library from the process after we check whether it is supported. This saves some resources when HTTP/3 is not used (e.g. the server does not advertise HTTP/3)

Test app:

using System.Net.Http;

HttpClient client = new HttpClient();

await client.GetAsync("https://www.microsoft.com");

System.Console.WriteLine("Done");
System.Console.ReadLine();

Results on Windows11

Diff	Before	After
Threads	62	23
PrivateMemorySize	13385728	12083200

Brings back PR #74749, reverted by PR #74984

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Issue Details

---

Brings back #74749, reverted by #74984

Author:	wfurt
Assignees:	-
Labels:	area-System.Net
Milestone:	-

[ghost]

Tagging subscribers to this area: @dotnet/ncl
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Brings back #74749, reverted by #74984

Author:	wfurt
Assignees:	wfurt
Labels:	area-System.Net, area-System.Net.Quic
Milestone:	-

[wfurt]

Debian 10 on ARM64 is OK
https://helixre107v0xdeko0k025g8.blob.core.windows.net/dotnet-runtime-refs-pull-75163-merge-ee93b0bfb1f4439da8/System.Net.Quic.Functional.Tests/1/console.99482cb3.log?helixlogtype=result

Console log: 'System.Net.Quic.Functional.Tests' from job ee93b0bf-b1f4-439d-a82a-e3bbd340118b (ubuntu.1804.armarch.open) using docker image mcr.microsoft.com/dotnet-buildtools/prereqs:debian-10-helix-arm64v8-20220906200500-06f234f on ddvsotx2l103


/root/helix/work/workitem/e /root/helix/work/workitem/e
  Discovering: System.Net.Quic.Functional.Tests (method display = ClassAndMethod, method display options = None)
  Discovered:  System.Net.Quic.Functional.Tests (found 106 of 112 test cases)
  Starting:    System.Net.Quic.Functional.Tests (parallel test collections = on, max threads = 6)
    System.Net.Quic.Tests.MsQuicPlatformDetectionTests.UnsupportedPlatforms_ThrowsPlatformNotSupportedException [SKIP]
      Condition(s) not met: "IsQuicUnsupported"
  Finished:    System.Net.Quic.Functional.Tests
=== TEST EXECUTION SUMMARY ===
   System.Net.Quic.Functional.Tests  Total: 326, Errors: 0, Failed: 0, Skipped: 1, Time: 124.431s

[rzikm]

Would you mind picking changes from #74985 here as well?

[rzikm]

LGTM!

[karelz]

@wfurt I assume your Debian 10 ARM64 validation above was with msquic 2.1.1 package. Can you please confirm?

[karelz]

Also, should we mark the PR as blocked until we finish updating msquic 2.1.1 properly? (incl. Windows source code snapshot)

[wfurt]

no, that is still floating in. It has Docker image based on dotnet/msquic main e.g. has startup changes but it is not the official bits.

[rzikm]

/backport to release/7.0

[github-actions]

Started backporting to release/7.0: https://github.com/dotnet/runtime/actions/runs/3020723954

[github-actions]

@rzikm backporting to release/7.0 failed, the patch most likely resulted in conflicts:

$ git am --3way --ignore-whitespace --keep-non-patch changes.patch

Applying: Revert "Revert "Unload MsQuic after checking for QUIC support to free resources. (#74749)" (#74984)"
Applying: update helix images
Using index info to reconstruct a base tree...
M	eng/pipelines/libraries/helix-queues-setup.yml
Falling back to patching base and 3-way merge...
Auto-merging eng/pipelines/libraries/helix-queues-setup.yml
CONFLICT (content): Merge conflict in eng/pipelines/libraries/helix-queues-setup.yml
error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
Patch failed at 0002 update helix images
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".
Error: The process '/usr/bin/git' failed with exit code 128

Please backport manually!