rename test/test-files -> test/files

Additional prefix is pretty useless, and I wanted to do this for a long
time now.

.gitattributes

@@ -10,7 +10,7 @@
 *.yml               text
 ### Documentation (Project, Tests, Docs site)
 *.md                text
-### TLS certs (test/test-files/) + DHE params (target/shared/)
+### TLS certs (test/files/) + DHE params (target/shared/)
 *.pem               text
 *.pem.sha512sum     text
 
@@ -90,9 +90,9 @@ TrustedHosts        text
 whitelist_recipients text
 
 ## MISC
-### test/config/ + test/test-files/
+### test/config/ + test/files/
 *.txt               text
-### test/linting/ (.ecrc.json) + test/test-files/ (*.acme.json):
+### test/linting/ (.ecrc.json) + test/files/ (*.acme.json):
 *.json              text
 
 #################################################

docs/content/config/security/ssl.md

@@ -880,7 +880,7 @@ Despite this, if you must use non-standard DH parameters or you would like to sw
 [docs-faq-baredomain]: ../../faq.md#can-i-use-a-nakedbare-domain-ie-no-hostname
 
 [github-file-compose]: https://github.com/docker-mailserver/docker-mailserver/blob/master/compose.yaml
-[github-file::tls-readme]: https://github.com/docker-mailserver/docker-mailserver/blob/3b8059f2daca80d967635e04d8d81e9abb755a4d/test/test-files/ssl/example.test/README.md
+[github-file::tls-readme]: https://github.com/docker-mailserver/docker-mailserver/blob/3b8059f2daca80d967635e04d8d81e9abb755a4d/test/files/ssl/example.test/README.md
 [hanscees-renewcerts]: https://github.com/hanscees/dockerscripts/blob/master/scripts/tomav-renew-certs
 
 [traefik::github]: https://github.com/containous/traefik

test/helper/setup.bash

@@ -98,7 +98,7 @@ function _init_with_defaults() {
 
   # Common complimentary test files, read-only safe to share across containers:
   export TEST_FILES_CONTAINER_PATH='/tmp/docker-mailserver-test'
-  export TEST_FILES_VOLUME="${REPOSITORY_ROOT}/test/test-files:${TEST_FILES_CONTAINER_PATH}:ro"
+  export TEST_FILES_VOLUME="${REPOSITORY_ROOT}/test/files:${TEST_FILES_CONTAINER_PATH}:ro"
 
   # The config volume cannot be read-only as some data needs to be written at container startup
   #