Remove SAST Analyzer SAST_GOSEC_CONFIG variable

SAST_GOSEC_CONFIG has been deprecated in favor of custom rulesets. We need to remove it from the product.

Remove CLI flag from gosec analyzer. gitlab-org/security-products/analyzers/gosec!106 (merged)
Update documentation to remove references to the variable. | !63518 (merged)
Update both SAST.gitlab-ci.yml and Secure-Binaries.gitlab-ci.yml to remove references to the variable and bump SAST_ANALYZER_IMAGE_TAG | !63547 (merged) | !63546 (closed)
Update integration tests to use custom rulesets.

Edited Jun 11, 2021 by Daniel Paul Searles