bazel should not build/test targets inside output_base if output_base is in source tree

### Description of the bug:

When we build/test with bazel in CI, we run with this command:

```
bazel --output_base=output test //...
```

However, if any external deps contain test targets, these are picked up by the build, evaluated in the context of outer workspace, and fail.

```
ERROR: Skipping '//...': error loading package under directory '': error loading package 'output/external/our_rules~/tests/lib/libb': cannot load '//:tools/defs.bzl': no such file
```

The question is: should the directory that bazel creates with --output_base be automatically ignored in build/test steps if it's inside the workspace?

### Which category does this issue belong to?

Core

### What's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

_No response_

### Which operating system are you running Bazel on?

windows

### What is the output of `bazel info release`?

bazel 7.2.1

### If `bazel info release` returns `development version` or `(@non-git)`, tell us how you built Bazel.

_No response_

### What's the output of `git remote get-url origin; git rev-parse HEAD` ?

_No response_

### If this is a regression, please try to identify the Bazel commit where the bug was introduced with bazelisk --bisect.

_No response_

### Have you found anything relevant by searching the web?

_No response_

### Any other information, logs, or outputs that you want to share?

_No response_