t/t4NNN: allow local submodules

To prepare for the default value of `protocol.file.allow` to change to
"user", ensure tests that rely on local submodules can initialize them
over the file protocol.

Tests that only need to interact with submodules in a limited capacity
have individual Git commands annotated with the appropriate
configuration via `-c`. Tests that interact with submodules a handful of
times use `test_config_global` instead. Test scripts that rely on
submodules throughout use a `git config --global` during a setup test
towards the beginning of the script.

Signed-off-by: Taylor Blau <me@ttaylorr.com>

t/t4059-diff-submodule-not-initialized.sh

@@ -49,7 +49,7 @@ test_expect_success 'setup - submodules' '
 '
 
 test_expect_success 'setup - git submodule add' '
-	git submodule add ./sm2 sm1 &&
+	git -c protocol.file.allow=always submodule add ./sm2 sm1 &&
 	commit_file sm1 .gitmodules &&
 	git diff-tree -p --no-commit-id --submodule=log HEAD -- sm1 >actual &&
 	cat >expected <<-EOF &&

t/t4060-diff-submodule-option-diff-format.sh

@@ -759,9 +759,9 @@ test_expect_success 'diff --submodule=diff with .git file' '
 '
 
 test_expect_success 'setup nested submodule' '
-	git submodule add -f ./sm2 &&
+	git -c protocol.file.allow=always submodule add -f ./sm2 &&
 	git commit -a -m "add sm2" &&
-	git -C sm2 submodule add ../sm2 nested &&
+	git -c protocol.file.allow=always -C sm2 submodule add ../sm2 nested &&
 	git -C sm2 commit -a -m "nested sub" &&
 	head10=$(git -C sm2 rev-parse --short --verify HEAD)
 '

t/t4067-diff-partial-clone.sh

@@ -77,6 +77,7 @@ test_expect_success 'diff skips same-OID blobs' '
 
 test_expect_success 'when fetching missing objects, diff skips GITLINKs' '
 	test_when_finished "rm -rf sub server client trace" &&
+	test_config_global protocol.file.allow always &&
 
 	test_create_repo sub &&
 	test_commit -C sub first &&

t/t4208-log-magic-pathspec.sh

@@ -126,6 +126,7 @@ test_expect_success 'command line pathspec parsing for "git log"' '
 
 test_expect_success 'tree_entry_interesting does not match past submodule boundaries' '
 	test_when_finished "rm -rf repo submodule" &&
+	test_config_global protocol.file.allow always &&
 	git init submodule &&
 	test_commit -C submodule initial &&
 	git init repo &&