cmd/go: remove TestScript/version_buildvcs_git_gpg

This was a regression test added for a 'git' command line
used for build stamping. Unfortunately, 'gpg' has proved to
be extremely fragile:

* In recent versions, it appears to always require 'gpg-agent' to be
  installed for anything involving secret keys, but for some reason is
  not normally marked as requiring gpg-agent in Debian's package
  manager.

* It tries to create a Unix domain socket in a subdirectory of $TMPDIR
  without checking the path length, which fails when $TMPDIR is too
  long to fit in the 'sun_path' field of a sockaddr_un struct (which
  typically tops out somewhere between 92 and 108 bytes).

We could theoretically address those by artificially reducing the
script's TMPDIR length and checking for gpg-agent in addition to gpg,
but arguably those should both be fixed upstream instead. On balance,
the incremental value that this test provides does not seem worth the
complexity of dealing with such a fragile third-party tool.

Updates #50675.
Updates #48802.
Fixes #57034.

Change-Id: Ia3288c2f84f8db86ddfa139b4d1c0112d67079ef
Reviewed-on: https://go-review.googlesource.com/c/go/+/454502
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Bryan Mills <bcmills@google.com>
Auto-Submit: Bryan Mills <bcmills@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>

src/cmd/go/testdata/script/version_buildvcs_git_gpg.txt

@@ -1,107 +0,0 @@
-# This test checks that VCS information is stamped into Go binaries even when
-# the current commit is signed and the use has configured git to display commit
-# signatures.
-
-[!git] skip
-[!exec:gpg] skip
-[short] skip
-env GOBIN=$GOPATH/bin
-env GNUPGHOME=$WORK/.gpupg
-mkdir $GNUPGHOME
-chmod 0700 $GNUPGHOME
-
-# Create GPG key
-exec gpg --batch --passphrase '' --quick-generate-key --verbose gopher@golang.org
-exec gpg --list-secret-keys --with-colons gopher@golang.org
-cp stdout keyinfo.txt
-go run extract_key_id.go keyinfo.txt
-cp stdout keyid.txt
-
-# Initialize repo
-cd repo/
-exec git init
-exec git config user.email gopher@golang.org
-exec git config user.name 'J.R. Gopher'
-exec git config --add log.showSignature true
-go run ../configure_signing_key.go ../keyid.txt
-
-# Create signed commit
-cd a
-exec git add -A
-exec git commit -m 'initial commit' --gpg-sign
-exec git log
-
-# Verify commit signature does not interfere with versioning
-go install
-go version -m $GOBIN/a
-stdout '^\tbuild\tvcs\.revision='
-stdout '^\tbuild\tvcs\.time='
-stdout '^\tbuild\tvcs\.modified=false$'
-
--- repo/README --
-Far out in the uncharted backwaters of the unfashionable end of the western
-spiral arm of the Galaxy lies a small, unregarded yellow sun.
--- repo/a/go.mod --
-module example.com/a
-
-go 1.18
--- repo/a/a.go --
-package main
-
-func main() {}
-
--- extract_key_id.go --
-package main
-
-import (
-	"fmt"
-	"os"
-	"strings"
-)
-
-func main() {
-	err := run(os.Args[1])
-	if err != nil {
-		panic(err)
-	}
-}
-
-func run(keyInfoFilePath string) error {
-	contents, err := os.ReadFile(keyInfoFilePath)
-	if err != nil {
-		return err
-	}
-	lines := strings.Split(string(contents), "\n")
-	for _, line := range lines {
-		fields := strings.Split(line, ":")
-		if fields[0] == "sec" {
-			fmt.Print(fields[4])
-			return nil
-		}
-	}
-	return fmt.Errorf("key ID not found in: %s", keyInfoFilePath)
-}
-
--- configure_signing_key.go --
-package main
-
-import (
-	"os"
-	"os/exec"
-)
-
-func main() {
-	err := run(os.Args[1])
-	if err != nil {
-		panic(err)
-	}
-}
-
-func run(keyIdFilePath string) error {
-	keyId, err := os.ReadFile(keyIdFilePath)
-	if err != nil {
-		return err
-	}
-	gitCmd := exec.Command("git", "config", "user.signingKey", string(keyId))
-	return gitCmd.Run()
-}