[Feature Request]: Allow environmental variable to control "Enabled" checkbox in (synchronous) webservices (metadata)

### What would you like to happen?

### What would you like to happen?

Follow-up of https://github.com/apache/hop/issues/5628.

For metadata object "Web Service" we would like to be able to control the "Enabled" checkbox via an environmental variable:

Documentation would include valid values for this variable, and the logic that is applied when the variable is empty/unset, or contains invalid values.
Similary, what would happen when the checkbox conflicts with the value of the variable.
Optimally, the checkbox would be greyed out when the config variable is used?

See also https://github.com/apache/hop/issues/5963.

### Issue Priority

Priority: 3

### Issue Component

Component: Hop Gui, Component: Metadata

### Issue Priority

Priority: 3

### Issue Component

Component: Hop Gui, Component: Metadata

Start by reading follow-up issue 5628 and related issue 5963, then trace the Web Service metadata Enabled setting in the Hop GUI metadata component. Define the environment variable's valid values and behavior when unset, invalid, or conflicting with the checkbox, document those rules, and determine whether the checkbox should be greyed out when configured.

Written by the indexing model from the issue text.