tractus-x: Update settings of repo `tractusx-edc`

Summary

Please change the following settings on https://github.com/eclipse-tractusx/tractusx-edc:

• enable GH discussions
• create a secret named TXDC_GHCR_PAT containing a PAT, with which we can publish artifacts to the repo's GitHub Packages.
• make develop the default branch (currently it is main)
• enable Pull-Request+Issue linking. don't know if that needs to be explicitly enabled, but ATM it does not work, e.g. this issue and this PR

Priority

• Urgent
• High
• Medium
• Low

Severity

• Blocker
• Major
• Normal
• Low

Impact

(What is the impact of this issue? Is it blocking a release? Are there any time constraints?, for example: "We have a release tomorrow")