Do not take protocol and port from custom Endpoint

[trivikr]

Issue #, if available:
Refs: aws/aws-sdk-js-v3#6410 (comment)

Description of changes:
Skips taking protocol and port from custom Endpoint.

The old tests added in aws/aws-sdk-js-v3#4031 were likely incorrect.
Noticed while incorporating the endpoint tests at top-level in aws/aws-sdk-js-v3#6410 (comment)

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[kuhe]

To clarify, this is not the removal of the user's ability to set a custom protocol and port.

If a service's ruleset follows the base template, one of the initial conditions is to check for a "built-in" user-supplied Endpoint parameter, or endpoint typically in TypeScript SDKs generated from Smithy.

It looks like this:

"conditions": [
  {
    "fn": "isSet",
    "argv": [
      {
        "ref": "Endpoint"
      }
    ]
  },
  {
    "fn": "parseURL",
    "argv": [
      {
        "ref": "Endpoint"
      }
    ],
    "assign": "url"
  }
],

And will resolve an endpoint template such as

"endpoint": {
  "url": "{url#scheme}://{url#authority}{url#path}",
  "...": "..."
}

This preserves the user's input scheme/protocol and port as part of authority.

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In rare cases where the service ruleset ignores the user input endpoint's scheme/port, the fix would be either to patch the ruleset or override the endpointProvider configuration field.