pool: improve err msg on mover create if protocol is not supported

Motivation:
When a pool is missing SSL certificates and thus https is not supported, an
attempt to download a file via https will result in something like the following error message:
`Internal problem: Protocol Https-1.1:<client address>:<client port>:<door cell>:<door domain>:<path> is not supported`

This string includes much information in addition to the protocol, potentially making it difficult to understand the root cause.

Modification:
Improve logged message to mirror the other MoverProtocol mover creation exception messages and specifically
highlight the protocol itself.

Result:
Clearer error message when MoverProtocol mover creation fails due to an unsupported protocol (e.g. https)

Target: master
Addresses: RT 10478
Requires-notes: no
Requires-book: no
Patch: https://rb.dcache.org/r/14112/
Acked-by: Dmitry Litvintsev

modules/dcache/src/main/java/org/dcache/pool/classic/AbstractMoverProtocolTransferService.java

@@ -1,6 +1,6 @@
 /* dCache - http://www.dcache.org/
  *
- * Copyright (C) 2015 - 2020 Deutsches Elektronen-Synchrotron
+ * Copyright (C) 2015 - 2023 Deutsches Elektronen-Synchrotron
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
@@ -84,8 +84,10 @@ public Mover<?> createMover(ReplicaDescriptor handle, PoolIoFileMessage message,
             throw new CacheException(CacheException.CANNOT_CREATE_MOVER, error,
                   cause);
         } catch (ClassNotFoundException e) {
-            throw new CacheException(CacheException.CANNOT_CREATE_MOVER,
-                  "Protocol " + info + " is not supported", e);
+            String error =
+                  "Could not create MoverProtocol mover for " + info + " because protocol "
+                        + info.getVersionString() + " is not supported";
+            throw new CacheException(CacheException.CANNOT_CREATE_MOVER, error, e);
         } catch (Exception e) {
             Throwables.throwIfUnchecked(e);
             String error = "Could not create MoverProtocol mover for " + info