Powershell provisioner's "environment_vars" configuration does not work when used with "scripts" configuration

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#### Overview of the Issue

When using the powershell provisioner to provision your packer deployment, any environment variables configured in the "environment_vars" config are not made available to the powershell scripts that are configured using the "scripts" config. This only occurs with the "scripts" config. The powershell provisioner works as expected (eg. the configured environment variables are made available to the powershell session) when you use the "script" or "inline" configs.

#### Reproduction Steps

1) In a packer config file, in the build block, define a powershell provisioner block that
- configures a couple of environment variables using the "environment_vars" config
- and runs a couple of powershell scripts that utilize the previously configured environment variables using the "scripts" config
2) Build the deployment using packer build .

### Packer version

packer -version
1.9.2

### Simplified Packer Template

https://gist.github.com/youngturk2/2dc369a5bc799f222e6db895d5b373f0

### Operating system and Environment details

The os installed on the packer deployment is windows server 2019. The build server running the packer build is windows server 2016

### Log Fragments and crash.log files

```
==> oracle-oci.server2019: Machine successfully restarted, moving on
==> oracle-oci.server2019: Provisioning with Powershell...
==> oracle-oci.server2019: Provisioning with powershell script: ../powershell/Invoke-DotNetOptimization.ps1
==> oracle-oci.server2019: Provisioning with powershell script: ../powershell/Install-PSResourceGet.ps1
oracle-oci.server2019: ConvertTo-SecureString : Cannot bind argument to parameter 'String' because it is null.
oracle-oci.server2019: At C:\Windows\Temp\script-64d11a98-7a20-a8fa-6a18-135c2da370[97](https://github.com/vertexinc/vod-oseries-oci-na/actions/runs/5787432178/job/15684360688#step:5:98).ps1:8 char:106
oracle-oci.server2019: + ... ial -ArgumentList "NA", (ConvertTo-SecureString $env:THETOKEN -AsPlai ...
oracle-oci.server2019: + ~~~~~~~~~~~~~
oracle-oci.server2019: + CategoryInfo : InvalidData: (:) [ConvertTo-SecureString], ParameterBindingValidationException
oracle-oci.server2019: + FullyQualifiedErrorId : ParameterArgumentValidationErrorNullNotAllowed,Microsoft.PowerShell.Commands.ConvertToSe
oracle-oci.server2019: cureStringCommand
oracle-oci.server2019:
oracle-oci.server2019: ConvertTo-SecureString : Cannot bind argument to parameter 'String' because it is null.
oracle-oci.server2019: At C:\Windows\Temp\script-64d11a[98](https://github.com/vertexinc/vod-oseries-oci-na/actions/runs/5787432178/job/15684360688#step:5:99)-7a20-a8fa-6a18-135c2da37097.ps1:9 char:37
oracle-oci.server2019: + $vaultpass = ConvertTo-SecureString $env:THEVAULTPASS -AsPlainText -F ...
oracle-oci.server2019: + ~~~~~~~~~~~~~~~~~
oracle-oci.server2019: + CategoryInfo : InvalidData: (:) [ConvertTo-SecureString], ParameterBindingValidationException
oracle-oci.server2019: + FullyQualifiedErrorId : ParameterArgumentValidationErrorNullNotAllowed,Microsoft.PowerShell.Commands.ConvertToSe
oracle-oci.server2019: cureStringCommand
oracle-oci.server2019:
oracle-oci.server2019: Creating a new Microsoft.PowerShell.SecretStore vault. A password is required by the current store configuration.
oracle-oci.server2019: Enter password:
Cancelling build after receiving interrupt
==> oracle-oci.server2019: Terminating instance (ocid1.instance.oc1.iad.anuwcljsf256y7ic3xwr2alpia3jqb5wew4hibzpdrloes4jmnnjiw3bzdmq)...
Error: The operation was canceled.
```