tests: Add missing module imports for marionette-evaluated code.

This missing imports became apparent with commit
a09c7da8f8, which runs the marionette
service in a fresh Guile process with fewer imports.

* gnu/tests/databases.scm (run-postgresql-test, run-timescaledb-test)
(run-mysql-test): Add missing module imports for code passed to
'marionette-eval'.
* gnu/tests/docker.scm (run-docker-test, run-docker-system-test): Likewise.
* gnu/tests/mail.scm (run-dovecot-test, run-getmail-test): Likewise.
* gnu/tests/monitoring.scm (run-zabbix-server-test): Likewise.
* gnu/tests/pam.scm (run-test-pam-limits): Likewise.
* gnu/tests/reconfigure.scm (run-switch-to-system-test)
(run-install-bootloader-test): Likewise.
* gnu/tests/security-token.scm (run-pcscd-test): Likewise.
* gnu/tests/install.scm (gui-test-program): Likewise.
* gnu/tests/telephony.scm (run-jami-test): Add modules to
the #:imported-modules argument of 'marionette-operating-system'.
[test]: Remove them from 'with-imported-modules'; remove
'with-extensions'.  Add "d-bus tooling loaded" test to set up %load-path
and %load-compiled-path so the marionette process can find
guile-ac-d-bus and guile-packrat.

gnu/tests/reconfigure.scm

@@ -104,10 +104,11 @@ generation of the system profile."
 
             (test-assert "script activated user accounts"
               (marionette-eval
-               '(string-contains (call-with-input-file "/etc/passwd"
-                                   (lambda (port)
-                                     (get-string-all port)))
-                                 "jakob")
+               '(begin
+                  (use-modules (rnrs io ports))
+                  (string-contains (call-with-input-file "/etc/passwd"
+                                     get-string-all)
+                                   "jakob"))
                marionette)))
 
           (test-end))))
@@ -208,9 +209,9 @@ bootloader's configuration file."
           (define (generations-in-grub-cfg marionette)
             (let ((grub-cfg (marionette-eval
                              '(begin
+                                (use-modules (rnrs io ports))
                                 (call-with-input-file "/boot/grub/grub.cfg"
-                                  (lambda (port)
-                                    (get-string-all port))))
+                                  get-string-all))
                              marionette)))
               (map (lambda (parameter)
                      (second (string-split (match:substring parameter) #\=)))