MDL-38343 cache: better test server strings

cache/stores/memcache/lang/en/cachestore_memcache.php

@@ -66,5 +66,5 @@
 </pre>';
 $string['sessionhandlerconflict'] = 'Warning: A memcache instance ({$a}) has being configured to use the same memcached server as sessions. Purging all caches will lead to sessions also being purged.';
 $string['testservers'] = 'Test servers';
-$string['testservers_desc'] = 'The test servers get used for unit tests and for performance tests. It is entirely optional to set up test servers. Servers should be defined one per line and consist of a server address and optionally a port and weight.
-If no port is provided then the default port (11211) is used.';
+$string['testservers_desc'] = 'One or more connection strings for memcache servers to test against. If a test server has been specified then memcache performance can be tested using the cache performance page in the administration block.
+As an example: 127.0.0.1:11211';

cache/stores/memcached/lang/en/cachestore_memcached.php

@@ -80,11 +80,11 @@
 </pre>';
 $string['sessionhandlerconflict'] = 'Warning: A memcached instance ({$a}) has being configured to use the same memcached server as sessions. Purging all caches will lead to sessions also being purged.';
 $string['testservers'] = 'Test servers';
-$string['testservers_desc'] = 'The test servers get used for unit tests and for performance tests. It is entirely optional to set up test servers. Servers should be defined one per line and consist of a server address and optionally a port and weight.
-If no port is provided then the default port (11211) is used.';
+$string['testservers_desc'] = 'One or more connection strings for memcached servers to test against. If a test server has been specified then memcached performance can be tested using the cache performance page in the administration block.
+As an example: 127.0.0.1:11211';
 $string['usecompression'] = 'Use compression';
 $string['usecompression_help'] = 'Enables or disables payload compression. When enabled, item values longer than a certain threshold (currently 100 bytes) will be compressed during storage and decompressed during retrieval transparently.';
 $string['useserialiser'] = 'Use serialiser';
 $string['useserialiser_help'] = 'Specifies the serializer to use for serializing non-scalar values.
 The valid serializers are Memcached::SERIALIZER_PHP or Memcached::SERIALIZER_IGBINARY.
-The latter is supported only when memcached is configured with --enable-memcached-igbinary option and the igbinary extension is loaded.';
+The latter is supported only when memcached is configured with --enable-memcached-igbinary option and the igbinary extension is loaded.';

cache/stores/mongodb/lang/en/cachestore_mongodb.php

@@ -35,7 +35,8 @@
 $string['server'] = 'Server';
 $string['server_help'] = 'This is the connection string for the server you want to use. Multiple servers can be specified using a comma-separated list.';
 $string['testserver'] = 'Test server';
-$string['testserver_desc'] = 'This is the connection string for the test server you want to use. Test servers are entirely optional, by specifiying a test server you can run PHPunit tests for this store and can run the performance tests.';
+$string['testserver_desc'] = 'The connection string for a server to use for testing. If a test server has been specified then MongoDB performance can be tested using the cache performance page in the administration block.
+As an example: mongodb://127.0.0.1:27017';
 $string['username'] = 'Username';
 $string['username_help'] = 'The username to use when making a connection.';
 $string['usesafe'] = 'Use safe';