Implement AZP_IGNORE_SECRETS_SHORTER_THAN knob

[KonstantinTyukalov]

Description: Implemented agent knob which allows to skip short secrets by setting min secret length of each secret.

Note that maximum length of secrets filter is 4

Changelog:

• Add AZP_IGNORE_SECRETS_SHORTER_THAN knob
• Updated vss-api-netcore to 0.5.181
• Update LoggedSecretMasker
• Added unit tests
• Some formatting
• Temporarily disabled removing of .pdb files from build
• Fixed api conflicts in VssAadToken and VssClientCredentials

Added unit tests:

• Yes

Attached related issue:

• Endpoint auth. parameter that is not confidential getting masked in agent logs #1207

Previous PR - #3962

Checklist:

• There are no risky dependency updates
• Changes have been tested

[StingyJack]

@KonstantinTyukalov please be sure that the solution is not going to be worse than the original problem. Nobody asked for secrets to be unmasked - that is worse than the problem reported where we can guess the secret values.

What if I made a build pipeline that used secrets I am not supposed to know and set the knob to 1000? I'm going to see all of the things I'm not supposed to see.

Also make sure its a feasible and reasonable suggestion. This proposal will require my org to put a variable into like 4K build pipelines. We should have to do nothing and change nothing - no knobulation should be required to have secrets masked appropriately. It just needs to work properly.

I know this is not an easy ask but its possible and there really are no shortcuts that are OK when it comes to security and diagnostics. I dont normally comment on another org's PR's but it doesnt look like you are incorporating what is said in the issue thread or the dev comm issues into these solutions, and any potential reviewer needs to understand that

[StingyJack]

@kirill-ivlev please take note of the comment above. This does not solve the problem and actually makes the problem worse.

[kirill-ivlev]

@StingyJack
thank you for your input, regarding long secrets we limited this knob to a maximum value of 4 characters.
For now, it should resolve cases when short secrets might leak from the logs.
We will check the other ways of resolving it in a more elegant way in the future.