@W-17247702: Remove getBuildConfigValue reflection usage

[wmathurin]

Replace reflection-based BuildConfig access with direct use of SDK's BuildConfig.DEBUG constant to fix obfuscation compatibility issues and ClassNotFoundException errors.

NB: The buildConfig feature was already enabled, the import com.salesforce.androidsdk.BuildConfig.DEBUG was already at the top of the file (line 74), but the code was still using reflection to access the consumer app's BuildConfig instead of the SDK's own BuildConfig.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 54.16%. Comparing base (a6fd61c) to head (0d68e71).
⚠️ Report is 4 commits behind head on dev.

❗ There is a different number of reports uploaded between BASE (a6fd61c) and HEAD (0d68e71). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (a6fd61c)	HEAD (0d68e71)
SalesforceSDK	2	1

Additional details and impacted files

@@              Coverage Diff              @@
##                dev    #2850       +/-   ##
=============================================
- Coverage     64.90%   54.16%   -10.74%     
+ Complexity     2963     2433      -530     
=============================================
  Files           222      222               
  Lines         17394    17382       -12     
  Branches       2478     2475        -3     
=============================================
- Hits          11289     9415     -1874     
- Misses         4906     6880     +1974     
+ Partials       1199     1087      -112     

Components	Coverage Δ
Analytics	47.92% <ø> (ø)
SalesforceSDK	39.71% <100.00%> (-20.02%)	⬇️
Hybrid	59.05% <ø> (ø)
SmartStore	78.20% <ø> (ø)
MobileSync	81.68% <ø> (ø)
React	52.36% <ø> (ø)

Files with missing lines	Coverage Δ
.../salesforce/androidsdk/app/SalesforceSDKManager.kt	33.45% <100.00%> (-25.98%)	⬇️

... and 56 files with indirect coverage changes

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