Edit Fuzzing docs metadata

doc/user/application_security/api_fuzzing/create_har_files.md

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 stage: Secure
-group: Fuzz Testing
+group: Dynamic Analysis
 info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#designated-technical-writers
 type: howto
 ---

doc/user/application_security/api_fuzzing/index.md

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 stage: Secure
-group: Fuzz Testing
+group: Dynamic Analysis
 info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments
 type: reference, howto
 ---

doc/user/application_security/coverage_fuzzing/index.md

 ---
 stage: Secure
-group: Fuzz Testing
+group: Dynamic Analysis
 info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments
 type: reference, howto
 ---