Fixes #9705: Prevent syntax error in startup.sh

[derdeagle]

If SESSION_DRIVER is not defined it leads to a syntax error.

Description

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Fixes #9705

Type of change

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• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

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• Manually set quotation marks at the necessary place inside of the container, start it and check the output / log file.

Test Configuration:
This should be irrelevant in this case.

Checklist:

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• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

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