MDEV-10368: get_latest_version() called too often

Reduce the number of calls to encryption_get_key_get_latest_version
when doing key rotation with two different methods:

(1) We need to fetch key information when tablespace not yet
have a encryption information, invalid keys are handled now
differently (see below). There was extra call to detect
if key_id is not found on key rotation.

(2) If key_id is not found from encryption plugin, do not
try fetching new key_version for it as it will fail anyway.
We store return value from encryption_get_key_get_latest_version
call and if it returns ENCRYPTION_KEY_VERSION_INVALID there
is no need to call it again.

Author: Jan Lindström

storage/innobase/buf/buf0buf.cc

@@ -6145,12 +6145,12 @@ buf_page_encrypt_before_write(
 		return src_frame;
 	}
 
-	if (crypt_data != NULL && crypt_data->encryption == FIL_SPACE_ENCRYPTION_OFF) {
+	if (crypt_data != NULL && crypt_data->not_encrypted()) {
 		/* Encryption is disabled */
 		encrypted = false;
 	}
 
-	if (!srv_encrypt_tables && (crypt_data == NULL || crypt_data->encryption == FIL_SPACE_ENCRYPTION_DEFAULT)) {
+	if (!srv_encrypt_tables && (crypt_data == NULL || crypt_data->is_default_encryption())) {
 		/* Encryption is disabled */
 		encrypted = false;
 	}