Add an option to remove brakeman attributes in JUnit report

[pbernery]

Is your feature request related to a problem? Please describe.
I encounter the issue declared in #1763: the JUnit report is refused by CircleCI.

Describe the solution you'd like
While there is a workaround proposed in the issue above, I wonder if an option to remove brakeman specific attributes won't be better? Or even remove the specific attributes at all: are they used by anyone? Hard to know I guess, but the original PR that introduced the JUnit format was for CircleCI support, but CircleCI does not support these additional attributes anymore.

Describe alternatives you've considered

• either add an option to remove those attributes,
• or remove those attributes.

Additional context
Add any other context or screenshots about the feature request here.

[presidentbeef]

Kind of confused about why these were added in the first place if they weren't valid. Looking at the original PR, seems like the attributes were specific to CircleCI and never valid for plain JUnit.

So yes I'm supportive of dropping them entirely.

[pbernery]

Alright. Then I will propose a PR to remove those attributes.
Thank you @presidentbeef.

[pbernery]

Here is a PR with the proposed changes: #1934.