fix: module not found errors on CE (#249)

# The problem

My pre-release e2e tests showed that workflows are failing with the
recent changes to our dockerfiles. @emre-aydin helped me find that
there's a problem with missing "ray" executable. We had a venv
auto-activation but I think some component (Workflow Driver?) runs a
different kind of shell.

# This PR's solution

Prefer to use `python`, `pip`, `ray`, etc from the venv owned by
`orquestra`.

I've confirmed the CPU dockerfiles to work by running our testing
workflows on `evil`. My procedure was:
1. `git tag v0.53.0.dev1`
2. `pip install .` (to have the client SDK set to the tagged version)
3. Trigger a build of SDK base image with version from (1)
4. Trigger a build of WDR dev image from WDR@main & SDK image from (2).
Publish it to `evil`
5. Run testing workflow
6. Check out `v0.52.0`
7. Repeat steps 2-5

# Checklist

_Check that this PR satisfies the following items:_

- [x] Tests have been added for new features/changed behavior (if no new
features have been added, check the box).
- [x] The [changelog file](CHANGELOG.md) has been updated with a
user-readable description of the changes (if the change isn't visible to
the user in any way, check the box).
- [x] The PR's title is prefixed with
`<feat/fix/chore/imp[rovement]/int[ernal]/docs>[!]:`
- [x] The PR is linked to a JIRA ticket (if there's no suitable ticket,
check the box).

docker/Dockerfile

@@ -40,6 +40,9 @@ python -m pip install --no-cache-dir -U pip wheel
 python -m pip install --no-cache-dir "${SDK_REQUIREMENT}"
 EOF
 
+# Prefer to use pip, python, and other binaries from the virtual env.
+ENV PATH="/opt/orquestra/venv/bin:$PATH"
+
 # This is needed to ensure that the virtual env is used when running
 # non-interactive shells (e.g. when running a startup script)
 # https://www.gnu.org/software/bash/manual/html_node/Bash-Startup-Files.html#Bash-Startup-Files

docker/cuda.Dockerfile

@@ -69,6 +69,9 @@ python -m pip install --no-cache-dir .
 python -m pip install --no-cache-dir "${SDK_REQUIREMENT}"
 EOF
 
+# Prefer to use pip, python, and other binaries from the virtual env.
+ENV PATH="/opt/orquestra/venv/bin:$PATH"
+
 # This is needed to ensure that the virtual env is used when running
 # non-interactive shells (e.g. when running a startup script)
 # https://www.gnu.org/software/bash/manual/html_node/Bash-Startup-Files.html#Bash-Startup-Files