When installing a single Python version, do not display number installed

[zanieb]

e.g.,

Searching for Python versions matching: any Python
Installed Python 3.12.3 to: /Users/zb/Library/Application Support/uv/python/cpython-3.12.3-macos-aarch64-none
Installed Python in 1.80s

instead of Installed 1 version in 1.80s

[T-256]

 Searching for Python versions matching: any Python
-Installed Python 3.12.3 to: /Users/zb/Library/Application Support/uv/python/cpython-3.12.3-macos-aarch64-none
-Installed Python in 1.80s
+Installed `cpython-3.12.3-macos-aarch64-none` in 1.80s

Getting install location is available by uv python dir, so I think it's better to prevent leak username for privacy 🤷‍♂️

[zanieb]

Could be nice to use the key there. Hm.

Idk about the install paths, we might need to consider that more holistically as part of #4896 as we do this all over the place right now.

[T-256]

Installed 1 python version in 25ms
 + cpython-3.12.3-macos-aarch64-none

Also, I think it's worth to match it to output design of uv pip install which is more stabled.

[charliermarsh]

Will take over.