Finally fix Metacello installation issues 🎉

We can simply skip the bootstraps process because an older version of
Metacello is already installed ... 🤦‍♂️ For more information, see:
Metacello/metacello#524 (comment)

Author: LinqLover

scripts/preLoading.st

@@ -1,7 +1,5 @@
 "Workaround for https://github.com/hpi-swa/smalltalkCI/pull/485 and https://github.com/Metacello/metacello/issues/524"
-Installer new installSAR: 'metacello2.sar' from: (
-	WebClient httpGet: 'https://gist.githubusercontent.com/LinqLover/8407df4997d465046920d9cd46a4e6f7/raw/8af1c40dc51564635b8e8ccf34919d4170b7c79d/metallo2.sar.base64')
-		content base64Decoded asByteArray readStream.
+SCIMetacelloLoadSpec updateMetacello.
 
 "Actual credentials configuration"
 MCFetchGithubRepository sitePassword: (SmalltalkCI getEnv: 'GITHUB_TOKEN').