text: Title: Using `format` as a query parameter for certain URLs causes `requests` to miss the `?` query string separator
  Body: <!-- Summary. -->
  Using `format` as a query parameter for certain URLs causes `requests` to miss the `?` query string separator
  
  ## Expected Result
  
  I expect the `?` separator to be present whenever any query parameters are provided.
  
  <!-- What you expected. -->
  
  ## Actual Result
  
  The `?` separator is not present.
  
  <!-- What happened instead. -->
  
  ## Reproduction Steps''
  
  ```python
  >>> import requests
  >>> requests.__version__
  '2.28.1'
  >>> requests.get("https://www.uniprot.org/uniprotkb/search", params={"format": "json"}).url
  'https://rest.uniprot.org/uniprotkb/searchformat=json'
  >>> requests.get("https://www.uniprot.org", params={"format": "json"}).url
  'https://rest.uniprot.org/format=json'
  >>> requests.get("https://www.uniprot.org/uniprotkb/search", params={"size": "500"}).url
  'https://www.uniprot.org/uniprotkb/search?size=500'
  >>> requests.get("https://www.google.com", params={"format": "json"}).url
  'https://www.google.com/?format=json'
  ```
  
  Note how the same issue happens in different subdomains of `uniprot.org` but that it doesn't happen with `google.com`
  
  ## System Information
  
      $ python -m requests.help
  
  ```json
  {
    "chardet": {
      "version": null
    },
    "charset_normalizer": {
      "version": "2.1.0"
    },
    "cryptography": {
      "version": ""
    },
    "idna": {
      "version": "3.3"
    },
    "implementation": {
      "name": "CPython",
      "version": "3.9.7"
    },
    "platform": {
      "release": "5.13.0-52-generic",
      "system": "Linux"
    },
    "pyOpenSSL": {
      "openssl_version": "",
      "version": null
    },
    "requests": {
      "version": "2.28.1"
    },
    "system_ssl": {
      "version": "101010cf"
    },
    "urllib3": {
      "version": "1.26.10"
    },
    "using_charset_normalizer": true,
    "using_pyopenssl": false
  }
  ```
  
  <!-- This command is only available on Requests v2.16.4 and greater. Otherwise,
  please provide some basic information about your system (Python version,
  operating system, &c). -->
  