fix: fix parsing of private_key_content in snowflake hooks

[rawwar]

fixes #47003

Copying comment from #47003 :

After converting the field to a BS3PasswordFieldWidget , when we paste PEM key with new lines, this field automatically removes new lines.

For example:

key_start
text
key_end
is now converted to a single line key_starttextkey_end .

And, when format the PEM key to replace new lines with "\n" , it is actually saved as "\n".

For example:
key_start\ntext\nkey_end to become key_start\ntext\nkey_end

Here's what I'm thinking to do:

Update docs to inform users to pass PEM key by replacing new lines with \n's
In the code, I'll just replace \n with \n

[potiuk]

As explained in #47003 -> I think better solution would be to extend the password widget to not replace the \n - alternatively we could extend the previous multi-line widget to use password type control and show **

[rawwar]

closing this as #49467 is merged