fix(cmake,docker): avoid cpp-httplib requiring brotli.

[FedeDP]

What type of PR is this?

/kind cleanup

Any specific area of the project related to this PR?

/area build

What this PR does / why we need it:

Since we started using ubuntu runner as builder (instead of relying on centos:7, see #3307), cpp-httplib started using brotli dep found in the system (that was not present on centos:7) since it defaults HTTPLIB_USE_BROTLI_IF_AVAILABLE to ON: https://github.com/yhirose/cpp-httplib/blob/master/CMakeLists.txt#L6

Disable this behavior since we do not want the added dep.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

NONE

[poiana]

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[FedeDP]

/milestone 0.40.0

/cc @leogr @LucaGuerra

Let's wait on the CI to build packages and check with ldd (i tested locally and it works btw).

[FedeDP]

This also reverts #3399

[LucaGuerra]

Thanks @FedeDP , as we discussed 🚀

[FedeDP]

/hold to run ldd on the generated executables.

[FedeDP]

ldd falco
	linux-vdso.so.1 (0x00007fff8cfdf000)
	libelf.so.1 => /lib/x86_64-linux-gnu/libelf.so.1 (0x000074a254fff000)
	libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x000074a254f16000)
	libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x000074a254f11000)
	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x000074a254c00000)
	libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x000074a254f0c000)
	librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x000074a254f05000)
	/lib64/ld-linux-x86-64.so.2 (0x000074a25503c000)
	libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x000074a254ee9000)
	libzstd.so.1 => /lib/x86_64-linux-gnu/libzstd.so.1 (0x000074a254e2f000)

Using the tar.gz provided by the CI.

vs On master:

ldd falco
	linux-vdso.so.1 (0x00007fff817ac000)
	libelf.so.1 => /lib/x86_64-linux-gnu/libelf.so.1 (0x0000705082af1000)
	libbrotlicommon.so.1 => /lib/x86_64-linux-gnu/libbrotlicommon.so.1 (0x0000705082ace000)
	libbrotlienc.so.1 => /lib/x86_64-linux-gnu/libbrotlienc.so.1 (0x0000705082a2f000)
	libbrotlidec.so.1 => /lib/x86_64-linux-gnu/libbrotlidec.so.1 (0x0000705082a21000)
	libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x0000705082938000)
	libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x0000705082931000)
	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x0000705082600000)
	libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x000070508292c000)
	librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x0000705082927000)
	/lib64/ld-linux-x86-64.so.2 (0x0000705082b2e000)
	libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x000070508290b000)
	libzstd.so.1 => /lib/x86_64-linux-gnu/libzstd.so.1 (0x0000705082851000)

/unhold