Fix db_config being nil in ActiveRecordSubscriber (#2111) #2588

Job	Run time
Ruby 2.4 & Rack 2, options - null	50s
Ruby 2.4 & Rack 3, options - null	54s
Ruby 2.5 & Rack 2, options - null	1m 5s
Ruby 2.5 & Rack 3, options - null	1m 7s
Ruby 2.6 & Rack 2, options - null	53s
Ruby 2.6 & Rack 3, options - null	1m 3s
Ruby 2.7 & Rack 2, options - null	1m 16s
Ruby 2.7 & Rack 3, options - null	55s
Ruby 3.0 & Rack 2, options - null	37s
Ruby 3.0 & Rack 3, options - null	59s
Ruby 3.1 & Rack 2, options - null	56s
Ruby 3.1 & Rack 3, options - null	36s
Ruby 3.2 & Rack 2, options - null	39s
Ruby 3.2 & Rack 3, options - null	40s
Ruby jruby & Rack 2, options - null	1m 44s
Ruby jruby & Rack 3, options - null	2m 27s
Ruby 3.2 & Rack 0, options - null	43s
Ruby 3.2 & Rack 2, options - null	38s
Ruby 3.2 & Rack 3, options - { "rubyopt": "--enable-frozen-string-literal --debug=frozen-string-literal" }	40s
Ruby 3.2 & Rack 3, options - { "codecov": 1 }	40s
	19m 22s

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