Fix runtime namespace links for vendor processes

This commit removes the soname filter from the namespace fallback link
from `runtime` to `system` in the vendor process.  This fixes the
problem that vendor process might fail to load `libnetd_client.so`,
`libc_malloc_debug.so`, `libc_malloc_debug_leak.so`, and other libc
dependencies.

This commit also removes the namespace fallback link from `runtime` to
`default` in the vendor process.  According to the comments in [1], the
original intention was to allow the access to `/system/${LIB}` not
`/vendor/${LIB}`.  Furthermore, `com.android.runtime` suppose to work
without libraries from `/vendor/${LIB}`.

[1] https://android-review.googlesource.com/c/858456

Bug: 119867084
Bug: 122025516  # Motivation of this commit
Test: Executables under vendor partition are not blocked by
`libnetd_client.so` not found error.

Change-Id: I682baada9d755910832474bb3d8307cd49c21ece