Resolve "Clean up cc7"

Summary

• Removed any presence of CC7 in if-statements (i.e. if alma9 do x, if cc7 do y). This means the entire if-statement was removed and the alma9 part is just the default execution
• Removed CC7 support from build scripts
• Removed docker/ctafrontend/cc7
• Removed CC7 build pod yml file
• Removed any if-statements such as if (ALMA9) or #ifdef ALMA9

Also removed two additional files that appear to be quite useless:

• Removed outdated README.md in docker/ctafrontend
• Removed outdated and unused build.Dockerfile from docker/ctafrontend/alma9

Additional Required Actions

• Requires manual tests in pre-production: NO

• Requires a documentation update: NO

References

Closes #811 (closed)