chore: remove unused configuration for building docs:guide

[trivikr]

Background

Running bundle exec rake docs:guide throws the following error:

mkdir -p doc
rm -rf doc/guide
bundle exec yard -q --yardopts .yardopts_guide
...
[warn]: Could not find file: doc-src/guide/index.md
[warn]: Could not find file: doc-src/guide/browser-intro.md
[warn]: Could not find file: doc-src/guide/browser-configuring.md
[warn]: Could not find file: doc-src/guide/browser-services.md
[warn]: Could not find file: doc-src/guide/browser-making-requests.md
[warn]: Could not find file: doc-src/guide/browser-examples.md
[warn]: Could not find file: doc-src/guide/browser-building.md
[warn]: Could not find file: doc-src/guide/browser-configuring-wif.md
[warn]: Could not find file: doc-src/guide/node-intro.md
[warn]: Could not find file: doc-src/guide/node-configuring.md
[warn]: Could not find file: doc-src/guide/node-services.md
[warn]: Could not find file: doc-src/guide/node-making-requests.md
[warn]: Could not find file: doc-src/guide/node-examples.md

This happens because the unused guide was removed in #1384, but the equivalent scripts were not removed.

Description

Removes scripts written for unused guide.
The new Developer Guide is hosted at https://docs.aws.amazon.com/sdk-for-javascript/v2/developer-guide/welcome.html

Testing

Verified that removed docs:all script is not used anywhere.

Checklist

• run bundle exec rake docs:api and inspect doc/latest/index.html if documentation is changed
• non-code related change (markdown/git settings etc)