Remove legacy sqlite source trees

The official sqlite release is now 3.50.6.  Remove the sqlite release
3.44, which was obsoleted in the previous release.  Note that main is
auto-merged into branches that use Android 16 flags, which means that
the Android 16 release (3.50.4) cannot be removed yet.

Flag: EXEMPT PURE_REFACTOR
Bug: 490153362
Test: presubmit
Change-Id: I50f02a4c03dfb22a5e8778de289c75b130597b72