Remove four asterisks in code comments (reserved for GAMS error messages)

[aodenweller]

Purpose of this PR

Sequences of four asterisks are reserved for GAMS error messages, but were inserted in code comments in cede734, bace67b and 06f746c. This replaces them.

Type of change

Only changing comments, not code.

• Bug fix

Checklist:

• My code follows the coding etiquette
• I performed a self-review of my own code
• I explained my changes within the PR, particularly in hard-to-understand areas
• I checked that the in-code documentation is up-to-date
• I adjusted the reporting in remind2 where it was needed
• I adjusted forbiddenColumnNames in readCheckScenarioConfig.R in case the PR leads to deprecated switches
• All automated model tests pass (FAIL 0 in the output of make test)
• The changelog CHANGELOG.md has been updated correctly

[cchrisgong]

Thanks! Was gonna submit one today.. you beat me to it :P