internal/buildcfg: enabled CoverageRedesign GOEXPERIMENT by default

Turn on the CoverageRedesign GOEXPERIMENT by default.

Updates #51430.

Change-Id: Id15c67ef0b6ac421b188d163fd2ce4a302abb3c9
Reviewed-on: https://go-review.googlesource.com/c/go/+/436236
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Than McIntosh <thanm@google.com>

src/internal/buildcfg/exp.go

@@ -70,9 +70,10 @@ func ParseGOEXPERIMENT(goos, goarch, goexp string) (*ExperimentFlags, error) {
 	}
 
 	baseline := goexperiment.Flags{
-		RegabiWrappers: regabiSupported,
-		RegabiArgs:     regabiSupported,
-		Unified:        true,
+		RegabiWrappers:   regabiSupported,
+		RegabiArgs:       regabiSupported,
+		Unified:          true,
+		CoverageRedesign: true,
 	}
 
 	// Start with the statically enabled set of experiments.