feat: DNF plugin: Read release only from cache file

* When there is cache file containing information about
  current release, then only this information is used
  for printing warning about release lock. Gathering such
  information from candlepin would be uneccessary slow
  down of DNF.

src/plugins/dnf/subscription_manager.py

@@ -24,7 +24,6 @@
 from subscription_manager.utils import chroot, is_simple_content_access
 from subscription_manager.injectioninit import init_dep_injection
 from subscription_manager.i18n import ungettext, ugettext as _
-from subscription_manager.release import get_consumer_release
 from rhsm import logutil
 from rhsm import config
 
@@ -33,11 +32,13 @@
 
 from configparser import ConfigParser
 
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Optional
 
 if TYPE_CHECKING:
     from subscription_manager.certdirectory import EntitlementDirectory
     from subscription_manager.identity import Identity
+    from subscription_manager.cache import ReleaseStatusCache
+    from subscription_manager.cp_provider import CPProvider
 
 
 expired_warning = _(
@@ -214,9 +215,22 @@ def _warn_or_give_usage_message():
             elif len(ent_dir.list_valid()) == 0 and not is_simple_content_access(identity=identity):
                 msg = no_subs_warning
             else:
-                release_version = get_consumer_release(identity=identity)
-                if release_version is not None:
-                    msg = release_lock_waring.format(release_version=release_version)
+                # Try to read release version ONLY from cache document.
+                # When cache document does not exist, then do not try to get this information
+                # from candlepin server and slow down DNF plugin!
+                release_cache: ReleaseStatusCache = inj.require(inj.RELEASE_STATUS_CACHE)
+                if release_cache.exists():
+                    release_version: Optional[str] = None
+                    cp_provider: CPProvider = inj.require(inj.CP_PROVIDER)
+                    cp = cp_provider.get_consumer_auth_cp()
+                    release_version_dict: Optional[dict] = release_cache.read_status(cp, identity.uuid)
+                    if release_version_dict is not None:
+                        try:
+                            release_version = release_version_dict["releaseVer"]
+                        except KeyError:
+                            log.warning("The 'releaseVer' not included in the release version document")
+                    if release_version is not None:
+                        msg = release_lock_waring.format(release_version=release_version)
         finally:
             if msg:
                 logger.info(msg)