Install fails if the stored config contains a GraphQL Server

Problem/Motivation

Install results in the following error.

>  [warning] Undefined variable $graphql_server acquia_perz.install:27
Error: Call to a member function id() on null in acquia_perz_install() (line 27 of /mnt/www/html/mskccdev/docroot/modules/contrib/acquia_perz/acquia_perz.install).
>  [error]  Error: Call to a member function id() on null in acquia_perz_install() (line 27 of /mnt/www/html/mskccdev/docroot/modules/contrib/acquia_perz/acquia_perz.install) #0 [internal function]: acquia_perz_install()

Steps to reproduce

1. Isolate the module into a Config Split set
2. Move a db from an environment in which the Config Split set is enabled to one in which it is not.
3. Move the db again to an environment in which the Config Split set is enabled again.

Proposed resolution

Adjust the install hook to account for the possibility that the GraphQL Server exists

Remaining tasks

None

User interface changes

None

API changes

None

Data model changes

None