build: do not apply curl debug macros to `tests/server` by default

build: do not apply curl debug macros to `tests/server` by default

It seems unnecessary and possibly unexpected to build test servers with
debug-enabled features and memory tracking whenever the tested curl is
built like that (which is a requirement for some tests, so curl is
mostly built like that when running tests.) It also makes building
servers a little bit faster with cmake for the most common cases.

You can apply debug options to `tests/server` with these new options:
- `./configure`: `--enable-server-debug`.
- cmake: `-DENABLE_SERVER_DEBUG`.

Also sync the way we pass these macros in autotools, with CMake builds.
Before this patch, autotools passed them via `curl_config.h`. After this
patch it passes them on the command-line, like cmake builds do.

This patch also make these option no longer passed to examples and
`http/client` in cmake builds, where they were no-ops anyway.

Ref: #15000
Closes #16705