[release] src/testUtils: adjust file path expansion regexp to capture subtest failures

Looks like verbose mode handling (json mode) already handles subtest error
messages as expected.

Fixes #956

Change-Id: I086076f1ab5435bd51f0956ec74e62d59e323531
Reviewed-on: https://go-review.googlesource.com/c/vscode-go/+/273048
Trust: Hyang-Ah Hana Kim <[email protected]>
Run-TryBot: Hyang-Ah Hana Kim <[email protected]>
TryBot-Result: kokoro <[email protected]>
Reviewed-by: Peter Weinberger <[email protected]>
(cherry picked from commit 8ea68d8)
Reviewed-on: https://go-review.googlesource.com/c/vscode-go/+/276212

Author: hyangah

src/testUtils.ts

@@ -497,7 +497,7 @@ function processTestResultLineInStandardMode(
 	outputChannel: vscode.OutputChannel) {
 	// 1=ok/FAIL/?, 2=package, 3=time/(cached)/[no test files]
 	const packageResultLineRE = /^(ok|FAIL|\?)\s+(\S+)\s+([0-9\.]+s|\(cached\)|\[no test files\])/;
-	const lineWithErrorRE = /^(\t|\s\s\s\s)\S/;
+	const lineWithErrorRE = /^\s+(\S+\.go):(\d+):/;
 
 	return (line: string) => {
 		testResultLines.push(line);