cleanup(libscap/kmod): remove ASSERT(false) on handled errors

[LucaGuerra]

What type of PR is this?

Uncomment one (or more) /kind <> lines:

/kind cleanup

Any specific area of the project related to this PR?

Uncomment one (or more) /area <> lines:

/area libscap-engine-kmod

Does this PR require a change in the driver versions?

No

What this PR does / why we need it:

These ASSERTS() look redundant since each error that they precede is handled and would make the program crash with a meaningful error either way. In addition, one test is actually throwing an error on purpose and may trigger one of these assert, aborting the test suite

Note: Google Test filter = sinsp.wrong_host_root
[==========] Running 1 test from 1 test suite.
[----------] Global test environment set-up.
[----------] 1 test from sinsp
[ RUN      ] sinsp.wrong_host_root
unit-test-libsinsp: /home/ubuntu/dev/falcosecurity/libs/userspace/libscap/engine/kmod/scap_kmod.c:171: mark_syscall: Assertion `0' failed.
Aborted

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

NONE

[FedeDP]

/approve

[poiana]

LGTM label has been added.

Git tree hash: d6f0fc2ec3c661b5778871740fe20cfaeacfc7ce

[Andreagit97]

/approve

[poiana]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Andreagit97, FedeDP, LucaGuerra

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