Content of $QA_HOME/files/qa-databases.conf must be *ADDED* to the file

$TESTING_FB_HOME/databases.conf rather than overwrite it.
Final file must contain aliases 'employee' and 'security.db'.
Otherwise in some cases attempt to made attach to Services can fail:
=======
	provider.set_dbcrypt_callback(crypt_callback)
	>           svc = provider.attach_service_manager(host, spb_buf)
	result = self.vtable.attachServiceManager(self, self.status, service.encode(), len(spb), spb)
	>       self._check()

	>           raise self.__report(DatabaseError, self.status.get_errors())
	firebird.driver.types.DatabaseError: Error occurred during login,
	please check server firebird.log for details
=======
And firebird.log contains at this moment:
	Authentication error
	I/O error during "CreateFile (open)" operation for file "...\SECURITY5.FDB"
	Error while trying to open file
	The system cannot find the file specified.
Detected on Windows, FB 5.0.0.970, Classic, test bugs/core_6316_test.py

Author: pavel-zotov

files/qa-databases.conf

@@ -1,14 +1,14 @@
-# QA-specific databases.conf, would be copied manually to $FB_HOME
+# QA-specific databases.conf, will be ADDED $FB_HOME/databases.conf
 # by batch scenario as part of preparation, before QA suite run.
+# ::: NB :::
+# DO NOT add here aliases 'employee', 'employee.fdb' and 'security.db'
+# ####################################################################
 # Discussed with pcisar, letters since 30-may-2022 13:48, subject:
-# "new qa, core_4964_test.py: strange outcome when use... shutil.copy() // comparing to shutil.copy2()"
-###################################################################
-
-employee.fdb = $(dir_sampleDb)/employee.fdb
-employee = $(dir_sampleDb)/employee.fdb
+# "new qa, core_4964_test.py: strange outcome when use... shutil.copy()"
+# ####################################################################
 
 # Hereafter we specify data for tests which require special settings for database.
-# NOTE: each alias must EXACTLY match to value specified in the test!
+# Each alias must EXACTLY match to value in the test, including letters case.
 #
 
 # Test issue: https://github.com/FirebirdSQL/firebird/issues/5160