net-snmp: Fix transitive headers for openssl

[AbrilRBS]

Fixes transitive header issues. Before this fixes, you'd get

[1/2] Building C object CMakeFiles/test_package.dir/test_package.c.o
FAILED: [code=1] CMakeFiles/test_package.dir/test_package.c.o 
/Users/ruben/.conan2/p/b/ccach31b575140aeb2/p/bin/ccache /usr/bin/cc -DPCRE_STATIC=1 -isystem /Users/ruben/.conan2/p/b/net-s59081d1b16d2f/p/include -isystem /Users/ruben/.conan2/p/opensca6fa8a584c20/p/include -isystem /Users/ruben/.conan2/p/zlibf7af9c3d20ae6/p/include -O3 -DNDEBUG -arch arm64 -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk -MD -MT CMakeFiles/test_package.dir/test_package.c.o -MF CMakeFiles/test_package.dir/test_package.c.o.d -o CMakeFiles/test_package.dir/test_package.c.o -c /Users/ruben/coding/conan-center-index/recipes/net-snmp/all/test_package/test_package.c
/Users/ruben/coding/conan-center-index/recipes/net-snmp/all/test_package/test_package.c:4:10: fatal error: 'net-snmp/transform_oids.h' file not found
    4 | #include <net-snmp/transform_oids.h>

with the updated test_package. After, the same test runs correctly

Closes #29236

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[memsharded]

Fix looks correct, failures in CI doesn't seem related to this change, it might be something else

[franramirez688]

We have bypassed the Linux CI building because of a missing CI tool (file), but we have tested this in our local environments, and it's building OK. We prefer to merge this till we have solved that issue on our CI machines.
Thanks, and sorry for any inconvenience!