Update test to be more flexible w/error message

[donoghuc]

This commit updates the expectation for the message when max bytes is exceeded to be more flexible. Instead of an exact match it expects a regex. This allows slight changes in the error message.

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[donoghuc]

This fixes all the cells other than SNAPSHOT=true ELASTIC_STACK_VERSION=main DOCKER_ENV=dockerjdk21.env. I believe this is likely due to a change in behavior with elastic/logstash@ba07878 It also seems related to #44 which is in progress

w Enable Watchlogstash-1  | Failures:
w Enable Watchlogstash-1  | 
w Enable Watchlogstash-1  |   1) LogStash::Codecs::JSONLines default parser choice behaves like codec #decode decode_size_limits_bytes should raise an error if the max bytes are exceeded
w Enable Watchlogstash-1  |      Failure/Error:
w Enable Watchlogstash-1  |        expect {
w Enable Watchlogstash-1  |          subject.decode(maximum_payload << "z")
w Enable Watchlogstash-1  |        }.to raise_error(java.lang.IllegalStateException, /input buffer full/)
w Enable Watchlogstash-1  |      
w Enable Watchlogstash-1  |        expected Java::JavaLang::IllegalStateException with message matching /input buffer full/ but nothing was raised
w Enable Watchlogstash-1  |      Shared Example Group: :codec called from ./spec/codecs/json_lines_spec.rb:240
w Enable Watchlogstash-1  |      # ./spec/codecs/json_lines_spec.rb:132:in `block in <main>'
w Enable Watchlogstash-1  | 
w Enable Watchlogstash-1  | Finished in 3.01 seconds (files took 11.34 seconds to load)
w Enable Watchlogstash-1  | 20 examples, 1 failure
w Enable Watchlogstash-1  | 
w Enable Watchlogstash-1  | Failed examples:
w Enable Watchlogstash-1  | 
w Enable Watchlogstash-1  | rspec ./spec/codecs/json_lines_spec.rb:131 # LogStash::Codecs::JSONLines default parser choice behaves like codec #decode decode_size_limits_bytes should raise an error if the max bytes are exceeded

[donoghuc]

The failure in main/9.2 is due to elastic/logstash#18321

For now the change proposed in this PR is still necessary, the fix for main/9.2 will be dependent on whatever we decide to do in logstash core.

[jsvd]

LGTM