ctx.actions.symlink doesn't make relative symlink, contrary to docs

ctx.actions.symlink always makes absolute symlinks when target_path is used, regardless of whether target_path is absolute.

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

**WORKSAPCE.bazel**

```py
```

**BUILD.bazel**

```py
load(":rules.bzl", "example")

example(
name = "example",
)
```

**rules.bzl**

```py
def _example_impl(ctx):
example1 = ctx.actions.declare_symlink("example1")
ctx.actions.symlink(output = example1, target_path = "../..")

example2 = ctx.actions.declare_symlink("example2")
ctx.actions.run(executable = "ln", arguments = ["-s", "../..", example2.path], outputs = [example2])

return DefaultInfo(
files = depset([example1, example2])
)

example = rule(
implementation = _example_impl
)
```

```
$ bazel build --experimental_allow_unresolved_symlinks :example
$ ls -l bazel-bin/
lrwxrwxrwx 1 paul paul 68 Nov 4 01:06 example1 -> /home/paul/.cache/bazel/_bazel_paul/fc54cd89f1e9b3d4a2b86f2842cad4ca
lrwxrwxrwx 1 paul paul 5 Nov 4 01:06 example2 -> ../..
```

I expected both symlinks to be ''../.." but only the latter (using executable ln) is.

Documentation: https://docs.bazel.build/versions/main/skylark/lib/actions.html#symlink

> (Experimental) **The exact path that the output symlink will point to. No normalization or other processing is applied.** Access to this feature requires setting --experimental_allow_unresolved_symlinks.

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

Ubuntu 18.04

### What's the output of `bazel info release`?

4.2.1

Start with the ctx.actions.symlink documentation and reproduce the behavior using the rules.bzl and BUILD.bazel examples. Run bazel build --experimental_allow_unresolved_symlinks :example and compare example1 with the ln-created example2; done means target_path="../.." produces the documented relative symlink.

Written by the indexing model from the issue text.