Fix incomplete Issue #110 - change PREMode default to NOT_SET

[BurakKTopal]

This PR replaces this original PR and fixes #110

The original fix in commit 64ed308 never worked because PREMode defaulted to INDCPA, not NOT_SET. This caused GetParamsPK() to always return Q×P basis for HYBRID, even when PRE is not needed.

Changes:

• Set default PREMode to NOT_SET in gen-cryptocontext-params-defaults.h
• Update pre-buffer.cpp to explicitly set PREMode=INDCPA

[dsuponitskiy]

Yuriy asked me to fix your original PR, so please do not reopen this one. We don’t need duplicate PRs. In addition, I’ve already started two extensive CI runs for the PR I opened.

[BurakKTopal]

@dsuponitskiy and @yspolyakov, I understand and respect the policy. If I may comment that I find the steps taken unusual: taking over someone else's work like this. I would have valued it a lot more to let me do it end-to-end and obtain full credits.

[yspolyakov]

@dsuponitskiy and @yspolyakov, I understand and respect the policy. If I may comment that I find the steps taken unusual: taking over someone else's work like this. I would have valued it a lot more to let me do it end-to-end and obtain full credits.

Hi @BurakKTopal Sorry you feel this way but I want to provide several clarifications to explain that your statement is not accurate.

1. The commit has your name. So no is taking over your work. You get the full credit, and it can be traced through the issue, PR, and discourse.
2. The initial PR was not submitted in the way we could process it. I asked you to resubmit the PR the way where we could run the CI. But since I did not get a response from you within 24 hours and we want to include this fix in the next (soon to be released) version (v1.5.0), I asked @dsuponitskiy to recreate the PR the proper way using your commit so that we could run CI for it.
3. In the future, I suggest creating PRs directly in the openfhe-development repo (and from the dev branch) so that we could process them without requiring unnecessary extra work from you or us.

Thank you for understanding.

Yuriy