hook_civicrm_entityTypes - Remove superfluous early-stage invocation

hook_civicrm_entityTypes - Remove superfluous early-stage invocation

Before
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TLDR: There are superfluous queries+hooks in every bootstrap. Specifically:

* During early stages of bootstrap, the extension system loads the `CRM_Extension_Manager_*` classes.
* The constructors for these classes lookup the option-group IDs in anticipation that they'll beeded.
* The lookup uses a helper method which relies on `hook_entityTypes`.
* Since all this happens during early bootstrap, `hook_entityTypes` becomes a preboot hook.
* But it's silly - because we don't actually these groupIds. They're only used during installation/uninstallation
  of obscure extensions.

After
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TLDR: Less superfluous queries+hooks.

* The `CRM_Extension_Manager_*` classes do not trigger any extraneous OG lookkups during bootstrap.
* The `CRM_Extension_Manager_*` will only do the query when it really needs to.
* `hook_entityTypes` fires later in bootstrap - when more services are available.