Simplify runtime test projects

[BruceForstall]

Don't specify defaults in the test project files, to simplify them:

1. CLRTestPriority of zero is the default, so don't specify that: commit 3d37868
2. CLRTestKind of BuildAndRun is the default, so don't specify that: commit 799129b

[BruceForstall]

/azp run runtime-coreclr outerloop

[dotnet-issue-labeler]

I couldn't figure out the best area label to add to this PR. If you have write-permissions please help me learn by adding exactly one area label.

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[ghost]

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

Issue Details

---

Don't specify defaults in the test project files, to simplify them:

1. CLRTestPriority of zero is the default, so don't specify that: commit 3d37868
2. CLRTestKind of BuildAndRun is the default, so don't specify that: commit 799129b

Author:	BruceForstall
Assignees:	-
Labels:	area-Infrastructure-coreclr
Milestone:	-

[BruceForstall]

The only test failure is #60152; others are infra failures.

The total number of outerloop tests remained the same (465,858).

[BruceForstall]

@dotnet/runtime-infrastructure PTAL.

Comments?

[jkoritzinsky]

I love the simplification!

[akoeplinger]

Nice! I assume we could simplify them even further by moving OutputType and AllowUnsafeBlocks to a common Directory.Build.props too?

[BruceForstall]

Nice! I assume we could simplify them even further by moving OutputType and AllowUnsafeBlocks to a common Directory.Build.props too?

Yeah, maybe it would make sense to make OutputType Exe the default and set that in src\tests\Directory.Build.targets along with the CLRTestKind/CLRTestPriority defaults.

AllowUnsafeBlocks is only set when needed, so I don't think that needs any cleanup.