Fix generate.sh from bad trap for ERR signal by using bash instead of sh

[noahkawasakigoogle]

What

Reports of some users seeing bad trap when running airbyte-integrations/connector-templates/generator/generate.sh because ERR does not exist in POSIX.

#5586

How

Use bash instead. I noticed a lot of the shell scripts in the repo use #!/usr/bin/env bash but a lot of the connectors use sh in the acceptance-test-docker.sh scripts. I was confused at first but it seems like the reason for this is that the generator docker image takes the last created connector and creates a template based off of that. So unless there was an intentional reason for using sh I think changing everything to bash now would solve this for the future until a linter rule is created to require bash.

Recommended reading order

1. x.java
2. y.python

🚨 User Impact 🚨

No user impact

Pre-merge Checklist

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This change is 

[CLAassistant]

All committers have signed the CLA.

[noahkawasakigoogle]

FYI I need to get an approval from my employer (Google) on signing the CLA first. They've got some processes around open source contributions

[noahkawasakigoogle]

Okay I got approval to sign the CLA, I can contribute to MIT licensed files, which this is. So should be okay to merge this one