after #1298, basic cleanup (first pass) of Eng Security page (#1299)

* after #1298, basic cleanup (first pass) of Eng Security page

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* add confidential information link

* Remove app passwords section

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* removed a lot and reorganized - stage one

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* removed external developer section

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>