Don't report "400 when POST-ing https://flowcrypt.com/attester/welcome-message" error

[sosnovsky]

We already have code for skipping this error - #5284, but these errors are reported again after manifest v3:

Bad Request: 400 when POST-ing https://flowcrypt.com/attester/welcome-message string: email,pubkey -> This key does not appear valid(Error: Could not find valid self-signature in key b4a63b803788e67e)

Maybe error text has changed and it's different from value in IGNORE_ERR_MSG array.

[martgil]

Upon checking, the error message we are checking is way too vast and so some other issue's that occurs on the /attester/welcome-message may still reports other issues.

So I think a way to solve this is to adjust the matching pattern regardless of the error text next to Bad Request: 400 when POST-ing https://flowcrypt.com/attester/welcome-message string: email,pubkey ->.