feat: allow Sentry uWSGI-plugin to be optional

Use ENABLE_SENTRY_UWSGI_PLUGIN-flag to control
Sentry uWSGI-plugin usage. Disable it by default.

Refs: PT-1958

Author: mhieta

.prod/uwsgi.ini

@@ -49,7 +49,7 @@ ignore-sigpipe = true
 ignore-write-errors = true
 disable-write-exception = true
 
-if-env = SENTRY_DSN
+if-env = ENABLE_SENTRY_UWSGI_PLUGIN
 print = Enabled sentry logging for uWSGI
 plugin = sentry
 alarm = logsentry sentry:dsn=$(SENTRY_DSN),logger=uwsgi.sentry