Change testSlowDripRedirectedOutputRedirectToSequence to guarding against the availability of SubprocessSpan like the other tests.

Author: Ryan Dingman

Tests/SubprocessTests/SubprocessTests+Unix.swift

@@ -666,8 +666,10 @@ extension SubprocessUnixTests {
         #expect(catResult.standardError == expected)
     }
 
-    @Test(.enabled(if: hasSubprocessSpan, "This test requires SubprocessSpan"))
-    func testSlowDripRedirectedOutputRedirectToSequence() async throws {
+    @Test func testSlowDripRedirectedOutputRedirectToSequence() async throws {
+        guard #available(SubprocessSpan , *) else {
+            return
+        }
         let threshold: Double = 0.5
 
         let script = """

Tests/SubprocessTests/TestSupport.swift

@@ -42,11 +42,3 @@ internal func directory(_ lhs: String, isSameAs rhs: String) -> Bool {
 
     return canonicalLhs == canonicalRhs
 }
-
-internal var hasSubprocessSpan: Bool {
-    if #available(SubprocessSpan , *) {
-        true
-    } else {
-        false
-    }
-}