tests: Adjust parallel tests

- The usual serial to parallel test conversion to utilize the `setup.bash` common setup structure, and adding a `TEST_PREFIX` var for each test case to leverage.
- Standardize on parallel test naming conventions for variables / values.
- More consistent use of `bash -c` instead of `/bin/bash -c` or `/bin/sh -c`.
- Using the `_run_in_container` helper instead of `run docker exec ${CONTAINER_NAME}`.
- Updates tests to use the `check_if_process_is_running` helper.

---

chore: Revise inline docs for the `ssl_letsencrypt` test

- Moves the override to be in closer proximity to the `initial_setup` call, and better communicates the intent to override.
- Removes top comment block that is no longer providing value or correct information to maintainers.
- Revised `acme.json` test case inline doc comments.

test/tests/parallel/set1/spam_virus/spam_bounced.bats

@@ -1,8 +1,8 @@
 load "${REPOSITORY_ROOT}/test/helper/setup"
 load "${REPOSITORY_ROOT}/test/helper/common"
 
-TEST_NAME_PREFIX='spam (Amavis):'
-CONTAINER_NAME='dms-test-spam_bounced'
+TEST_NAME_PREFIX='Spam bounced:'
+CONTAINER_NAME='dms-test_spam-bounced'
 
 function setup_file() {
   init_with_defaults