mbedtls: component CMakeLists.txt corrections

mbedtls: component CMakeLists.txt corrections

Since !4452 the common component requirements automatically get
privately linked to libraries built under ESP-IDF build system (this
includes targets from third-party libraries). This removes a variable
that was used for that purpose before !4452.

Since the internal target names were changed, the compile definition for
warning on using deprecated functions is not being passed. Since using
the internal name is unreliable, prefer passing this compile definition
from the test itself.