refactor(programs): use if let Some instead of unwrap for not is_none

[kskalski]

Problem

The code in process_loader_upgradeable_instruction( is checking option twice:

if x.is_none() {  // here
} else {
   ... x.unwrap()  // again here
} 

Summary of Changes

Flip if branches such that if let Some(x) = x can be used instead

Note: this was caught with newer (1.92) rust toolchain and emits warning, which this PR is fixing

[mergify]

The Firedancer team maintains a line-for-line reimplementation of the
native programs, and until native programs are moved to BPF, those
implementations must exactly match their Agave counterparts.
If this PR represents a change to a native program implementation (not
tests), please include a reviewer from the Firedancer team. And please
keep refactors to a minimum.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 30.00000% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.6%. Comparing base (4065e4a) to head (284bd21).
⚠️ Report is 3 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #10069   +/-   ##
=======================================
  Coverage    82.6%    82.6%           
=======================================
  Files         844      844           
  Lines      316607   316607           
=======================================
+ Hits       261552   261565   +13     
+ Misses      55055    55042   -13     

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