tests: remove uses of GIT_TEST_GETTEXT_POISON=false

As noted in previous commits we are removing the use of
GIT_TEST_GETTEXT_POISON=false. These tests all relied on the facility
being off, it always is off after an earlier change, but we hadn't
removed the redundant assignments to "false" in the tests.

I'm preserving the deletion of "error" lines in 38b9197a76 (t5411:
add basic test cases for proc-receive hook, 2020-08-27), it turns out
that's useful even without GIT_TEST_GETTEXT_POISON=true in
play. Update a comment added in that commit to note that.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t1305-config-include.sh

@@ -352,9 +352,7 @@ test_expect_success 'include cycles are detected' '
 	git init --bare cycle &&
 	git -C cycle config include.path cycle &&
 	git config -f cycle/cycle include.path config &&
-	test_must_fail \
-		env GIT_TEST_GETTEXT_POISON=false \
-		git -C cycle config --get-all test.value 2>stderr &&
+	test_must_fail git -C cycle config --get-all test.value 2>stderr &&
 	grep "exceeded maximum include depth" stderr
 '
 

t/t5411/common-functions.sh

@@ -36,9 +36,8 @@ create_commits_in () {
 # without having to worry about future changes of the commit ID and spaces
 # of the output.  Single quotes are replaced with double quotes, because
 # it is boring to prepare unquoted single quotes in expect text.  We also
-# remove some locale error messages, which break test if we turn on
-# `GIT_TEST_GETTEXT_POISON=true` in order to test unintentional translations
-# on plumbing commands.
+# remove some locale error messages. The emitted human-readable errors are
+# redundant to the more machine-readable output the tests already assert.
 make_user_friendly_and_stable_output () {
 	sed \
 		-e "s/  *\$//" \

t/t7201-co.sh

@@ -245,7 +245,7 @@ test_expect_success 'checkout to detach HEAD' '
 	rev=$(git rev-parse --short renamer^) &&
 	git checkout -f renamer &&
 	git clean -f &&
-	GIT_TEST_GETTEXT_POISON=false git checkout renamer^ 2>messages &&
+	git checkout renamer^ 2>messages &&
 	grep "HEAD is now at $rev" messages &&
 	test_line_count -gt 1 messages &&
 	H=$(git rev-parse --verify HEAD) &&

t/t9902-completion.sh

@@ -2363,7 +2363,6 @@ test_expect_success 'sourcing the completion script clears cached commands' '
 '
 
 test_expect_success 'sourcing the completion script clears cached merge strategies' '
-	GIT_TEST_GETTEXT_POISON=false &&
 	__git_compute_merge_strategies &&
 	verbose test -n "$__git_merge_strategies" &&
 	. "$GIT_BUILD_DIR/contrib/completion/git-completion.bash" &&