Remove obsoleted and non-working makefile targets

Those targets were either pulling an obsoleted container or failed to
build a custom one. Use-case of those targets is covered by pulling
openqa_devel container and running make run-tests-within-container
within that container.

Reference: https://progress.opensuse.org/issues/159747

Makefile

@@ -23,7 +23,6 @@ CHECKSTYLE ?= 0
 PROVE_ARGS ?= --trap ${EXTRA_PROVE_ARGS} $(TESTS)
 endif
 PROVE_LIB_ARGS ?= -l
-CONTAINER_IMG ?= openqa:latest
 TEST_PG_PATH ?= /dev/shm/tpg
 # TIMEOUT_M: Timeout for one retry of tests in minutes
 TIMEOUT_M ?= 60
@@ -40,7 +39,6 @@ LANGUAGE =
 LANG = C.utf8
 mkfile_path := $(abspath $(lastword $(MAKEFILE_LIST)))
 current_dir := $(patsubst %/,%,$(dir $(mkfile_path)))
-container_env_file := "$(current_dir)/container.env"
 unstables := $(shell cat tools/unstable_tests.txt | tr '\n' :)
 shellfiles := $$(file --mime-type script/* t/* container/worker/*.sh tools/* | sed -n 's/^\(.*\):.*text\/x-shellscript.*$$/\1/p')
 
@@ -283,25 +281,6 @@ public/favicon.ico: assets/images/logo.svg
 	convert assets/images/logo-16.png assets/images/logo-32.png assets/images/logo-64.png assets/images/logo-128.png -background white -alpha remove public/favicon.ico
 	rm assets/images/logo-128.png assets/images/logo-32.png assets/images/logo-64.png
 
-.PHONY: container-test-build
-container-test-build:
-	${CRE} build --no-cache $(current_dir)/container/openqa -t $(CONTAINER_IMG)
-
-.PHONY: $(container_env_file)
-$(container_env_file):
-	env | grep -E 'CHECKSTYLE|FULLSTACK|UITEST|GH|TRAVIS|CPAN|DEBUG|ZYPPER' > $@
-
-.PHONY: launch-container-to-run-tests-within
-launch-container-to-run-tests-within: $(container_env_file)
-	${CRE} run --env-file $(container_env_file) -v $(current_dir):/opt/openqa \
-	   $(CONTAINER_IMG) make coverage-codecov
-	rm $(container_env_file)
-
-.PHONY: prepare-and-launch-container-to-run-tests-within
-.NOTPARALLEL: prepare-and-launch-container-to-run-tests-within
-prepare-and-launch-container-to-run-tests-within: container-test-build launch-container-to-run-tests-within
-	echo "Use '${CRE} rm' and '${CRE} rmi' to remove the container and image if necessary"
-
 # all additional checks not called by prove
 .PHONY: test-checkstyle-standalone
 test-checkstyle-standalone: test-shellcheck test-yaml test-critic test-shfmt