Replace escaped translations with proper function

[obenland]

There are ten instances of esc_attr( __() ) across the WordPress codebase, as of revision 29927.
Replacing them with esc_attr__() would be a great opportunity for a beginning contributor to get their feet wet.

There is also one instance of esc_html( _x() ) that could be replaced with esc_html_x().

[jcastaneda]

Found a little more than 10 running trunk.

[jcastaneda]

Forgot esc_html_x().

[SergeyBiryukov]

wp-includes/script-loader.php can be included when esc_attr__() is not yet available, but it does not run it until did_action( 'init' ), so 30012.2.diff​ should work.

[SergeyBiryukov]

In 29961:

Use proper functions for escaped translations.

pros jcastaneda.
fixes #30012.