Fix kokoro presubmits!

Fixed the following error:
tools/bazel.mk:119: *** Destination not provided..  Stop.
The issue was that we were running all make commands in a subshell so variables
like $T were not passed on.

The other issue was related to credentials. The test passed locally but not on
kokoro, the only difference in the workflow was the credentials bit.

Also fixed up some other tiny issues I came across, were not blockers.

PiperOrigin-RevId: 322782457

Makefile

@@ -16,7 +16,7 @@
 
 # Helpful pretty-printer.
 MAKEBANNER := \033[1;34mmake\033[0m
-submake = echo -e '$(MAKEBANNER) $1' >&2; sh -c '$(MAKE) $1'
+submake = echo -e '$(MAKEBANNER) $1' >&2; $(MAKE) $1
 
 # Described below.
 OPTIONS :=

tools/bazel.mk

@@ -30,9 +30,6 @@ DOCKER_SOCKET := /var/run/docker.sock
 
 # Bazel flags.
 OPTIONS += --test_output=errors --keep_going --verbose_failures=true
-ifneq ($(AUTH_CREDENTIALS),)
-OPTIONS += --auth_credentials=${AUTH_CREDENTIALS} --config=remote
-endif
 BAZEL := bazel $(STARTUP_OPTIONS)
 
 # Non-configurable.
@@ -71,7 +68,7 @@ SHELL=/bin/bash -o pipefail
 bazel-server-start: load-default ## Starts the bazel server.
 	@mkdir -p $(BAZEL_CACHE)
 	@mkdir -p $(GCLOUD_CONFIG)
-	@if docker ps --all | grep $(DOCKER_NAME); then docker rm $(DOCKER_NAME); fi
+	@if docker ps --all | grep $(DOCKER_NAME); then docker rm -f $(DOCKER_NAME); fi
 	docker run -d --rm \
 		--init \
 	        --name $(DOCKER_NAME) \
@@ -102,7 +99,7 @@ bazel-server: ## Ensures that the server exists. Used as an internal target.
 	@docker exec $(DOCKER_NAME) true || $(MAKE) bazel-server-start
 .PHONY: bazel-server
 
-build_cmd = docker exec --user $(UID):$(GID) -i $(DOCKER_NAME) sh -o pipefail -c '$(BAZEL) $(STARTUP_OPTIONS) build $(OPTIONS) $(TARGETS)'
+build_cmd = docker exec --user $(UID):$(GID) -i $(DOCKER_NAME) sh -o pipefail -c '$(BAZEL) build $(OPTIONS) $(TARGETS)'
 
 build_paths = $(build_cmd) 2>&1 \
 		| tee /proc/self/fd/2 \