fix: CI module build cppcheck

[sogladev]

fixes module build errors due to failing cppcheck https://github.com/azerothcore/mod-zone-difficulty/actions/runs/12699226019/job/35399414259

�[1mmodules/mod-zone-difficulty/src/mod_zone_difficulty_handler.cpp:123:63: �[31merror:�[39m Uninitialized variables: data.HealingNerfPctHard, data.AbsorbNerfPctHard, data.SpellDamageBuffPctHard, data.MeleeDamageBuffPctHard [uninitvar]�[0m
                sZoneDifficulty->NerfInfo[mapId][phaseMask] = data;
                                                              ^
�[1mmodules/mod-zone-difficulty/src/mod_zone_difficulty_handler.cpp:242:69: �[31mwarning:�[39m Uninitialized variables: data.NormalOverride, data.MythicOverride [uninitvar]�[0m
                sZoneDifficulty->CreatureOverrides[creatureEntry] = data;
...

changes:
initialize variables by setting default values

default values from tables:

mod-zone-difficulty/data/sql/db-world/zone_difficulty_info.sql

Line 5 in 0e0b185

`HealingNerfValue` FLOAT NOT NULL DEFAULT 1,

mod-zone-difficulty/data/sql/db-world/zone_difficulty_mythicmode_creatureoverrides.sql

Line 4 in 0e0b185

`HPModifier` FLOAT NOT NULL DEFAULT 1,

Test

Run cppcheck from CI locally
https://github.com/azerothcore/reusable-workflows/blob/main/.github/workflows/core_build_modules.yml

cppcheck --force --inline-suppr --suppressions-list=cppchecksuppressions.txt --output-file=report.txt modules/

https://github.com/azerothcore/reusable-workflows/blob/4de2039354f9ac4565f6a079196f8b33f2e2a93e/cppchecksuppressions.txt#L2