[PyROOT] Retain C++ memory ownership for TStyle

[guitargeek]

Similar to 18a7c1f, since also any instantiated TStyle is owned by ROOT.

Closes #16918.

See:
https://github.com/root-project/root/blob/master/core/base/src/TStyle.cxx#L212

[vepadulano]

Very good! Could you also add the reproducer from the issue as a test? This way once hopefully we work our way out of the memory regulation logic we can make sure also this case is covered

[guitargeek]

Sure! I added the test

[github-actions]

Test Results

    19 files      19 suites   3d 23h 24m 51s ⏱️
 2 665 tests  2 665 ✅ 0 💤 0 ❌
48 742 runs  48 742 ✅ 0 💤 0 ❌

Results for commit 283164f.