Shortened instructions to reflect Alex's changes

Author: martig7

_docs/developer/testing/php_unit_tests.md

@@ -8,32 +8,13 @@ To validate the unit behavior of the site code, we utilize
 
 ### Dependencies
 
-Before running PHP Unit Tests, you must install the required dependencies. You may either run your tests locally or inside the VM:
-
-##### Inside the Vagrant VM
+Before running PHP Unit Tests, you must install the required dependencies:
 
 1. Install [Composer](https://getcomposer.org/download/) through the command-line installation copy-paste.
 2. `cd` to `/usr/local/submitty/GIT_CHECKOUT/Submitty/site/`.
 3. run  `composer update`
 
-*Please be aware that many unit tests will not work inside the VM. It is suggested that you run tests individually.*
-
-##### On Mac
-
-1. Install [Composer](https://getcomposer.org/download/) using brew.
-2. `cd` to your `Submitty/site/` folder.
-3. run `composer install`
-
-##### On Windows (Not Suggested)
-
-1. Navigate to your php folder, and open the php configuration settings file.
-2. Ctrl-F and uncomment the line labelled `extension=fileinfo` (remove the semi-colon). Do the same for the line labelled `extension=sodium`.
-3. Install [Composer](https://getcomposer.org/download/), click the link labelled Composer-Setup.exe.
-4. Restart your terminal.
-5. `cd` to your `Submitty/site/` folder.
-6. Run `composer update`. If you are getting timeout errors, try using a VPN.
-
-*This is not a good way to run unit tests because many file paths will be broken. Like with the vagrant VM, it is suggested that you run tests individually.*
+*If tests are failing on main, you may need to run `apt install php-sqlite3`, especially if you haven't vagrant upped from scratch in a while.*
 
 ### Running PHP Unit Tests
 
@@ -42,7 +23,7 @@ Before running PHP Unit Tests, you must install the required dependencies. You m
 To run the PHP unit test suite locally, `cd` to `/usr/local/submitty/GIT_CHECKOUT/Submitty/site/` and type:
 
 ```
-php vendor/bin/phpunit
+sudo -u submitty_php php vendor/bin/phpunit
 ```
 
 To run just an individual class or test, you can use the `--filter` flag on PHPUnit.