Tests: Remove .seconds-based timeouts in some Suites

[AnupamKumar-1]

Refactor testSwiftRunSIGINT to use XCTestExpectation instead of DispatchGroup timeout

Motivation:

The existing testSwiftRunSIGINT() relied on a 60 s DispatchGroup.wait(timeout:), which led to flaky CI failures and unnecessarily long test runs. We want the test to react immediately to the process’s “sleeping” output and its subsequent exit, rather than guessing at a timeout duration.

Modifications:

• Removed DispatchGroup and its 60 s timeout from testSwiftRunSIGINT().
• Introduced an XCTestExpectation (startedExp) that’s fulfilled when the child process prints “sleeping.”
• Inlined the stdout handler closures in the AsyncProcess initialization to detect the “sleeping” line and fulfill startedExp.
• Replaced the manual wait with wait(for: [startedExp], timeout: 10.0) to pause until the process is ready.
• Sent SIGINT immediately after that expectation and then called process.waitUntilExit().
• Removed the XCTSkipIf…CI guards now that the test is deterministic and reliably passes.

Result:

• testSwiftRunSIGINT() now completes in seconds instead of minutes and no longer fails intermittently on CI.
• The test suite runs faster and more reliably, with no arbitrary timeouts.

Fixes: #8770