Unable to get a manually installed plugin to load

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#### Overview of the Issue

We are unable to make a manually-installed plugin work. Our scenario is that we have a custom version of the OpenStack plugin, which we want to test alongside the stock Ansible plugin specified in the `packer` block:
```
packer {
required_plugins {
ansible = {
source = "github.com/hashicorp/ansible"
version = "~> 1"
}
}
}
```
Our custom build of the OpenStack plugin is installed in the same directory (`/usr/local/bin`) as the Packer binary itself. According to the trace, the plugin is "discovered" but then an error is produced that the file just found doesn't exist, a configuration error.

What we've tried to fix this:

- Various plugin binary permissions: `0777`, `0755`
- Various plugin binary owners: `root` (to match the Packer binary), `ci-pipeline-build` (the user executing Packer)
- Various naming for the plugin: `packer-plugin-openstack`, `packer-plugin-openstack_v1.1.1_x5.0_linux_amd64`
- Various locations for the plugin: `/usr/local/bin`; `/home/ci-pipeline-builder/.config/packer/plugins/`; `/home/ci-pipeline-builder/.config/packer/plugins/github.com/hashicorp/openstack/`

#### Reproduction Steps

Clone plugin repo:
```
git clone https://github.com/hashicorp/packer-plugin-openstack.git
```

Build repo:
```
go build
```

Copy built binary to directory where Packer binary lives:
```
cp packer-plugin-openstack /usr/local/bin/
chmod 0777 packer-plugin-openstack
chown root:root packer-plugin-openstack
```

Execute Packer build:
```
# Packer v1.9.4 requires init to fetch plugins
export PR_CFG="packer-runner.pkr.hcl"
PACKER_PLUGIN_PATH="/usr/local/bin" PACKER_LOG=1 packer init "${PR_CFG}"

PACKER_PLUGIN_PATH="/usr/local/bin" PACKER_LOG=1 packer plugins installed

PACKER_PLUGIN_PATH="/usr/local/bin" PACKER_LOG=1 packer validate "${PR_CFG}"

PACKER_PLUGIN_PATH="/usr/local/bin" PACKER_LOG=1 packer build "${PR_CFG}"
```

### Packer version
v1.9.4

### Simplified Packer Template

TBC

### Operating system and Environment details

Executing in a GitLab runner Docker container

Alpine Linux: `alpine:3.15.4`

### Log Fragments and crash.log files

Note in the following there's no output from the `packer plugins installed` command, so it seems the `init` must be failing?
```

2023/12/06 15:53:54 [INFO] Packer version: 1.9.4 [go1.20.7 linux amd64]
2023/12/06 15:53:54 [TRACE] discovering plugins in /usr/local/bin
2023/12/06 15:53:54 [INFO] Discovered potential plugin: openstack = /usr/local/bin/packer-plugin-openstack
Error loading configuration:
fork/exec /usr/local/bin/packer-plugin-openstack: no such file or directory

```
At that point the runner process fails and cleans up.

Start with the packer-plugin-openstack repository and reproduce the reported `go build`, copy, `packer init`, and `packer plugins installed` commands on Alpine Linux. Compare plugin discovery in `/usr/local/bin` with the subsequent `fork/exec ... no such file or directory` error; done means the manually built OpenStack plugin loads successfully alongside the configured Ansible plugin.

Written by the indexing model from the issue text.