[CR126] Eliminate need to patch out optimize_webui in read_anything BUILD.gn

[emerick]

Description

In order to work around a build problem in CR126, we had to patch out the use of optimize_webui in //chrome/browser/resources/side_panel/read_anything/BUILD.gn. We should investigate how to avoid this patch.

Build error was:

[!] Error: Could not load gen/ui/webui/resources/tsc/brave/br_elements/br_shared_vars.css.js (imported by gen/ui/webui/resources/tsc/cr_elements/cr_shared_vars.css.js): ENOENT: no such file or directory, open 'gen/ui/webui/resources/tsc/brave/br_elements/br_shared_vars.css.js'
Error: Could not load gen/ui/webui/resources/tsc/brave/br_elements/br_shared_vars.css.js (imported by gen/ui/webui/resources/tsc/cr_elements/cr_shared_vars.css.js): ENOENT: no such file or directory, open 'gen/ui/webui/resources/tsc/brave/br_elements/br_shared_vars.css.js'