The root CA used so far (GlobalSign R2) is about to expire soon
(December 2021) and Google have switched to a new certificate, signed by
GlobalSign R1 (valid until 2028). Therefore we need to replace the
root CA used by the sample to the new one, in order to establish secure
connection to with google.com.
Additionally, the new certificate chain sent by Google is larger again,
so it's needed to increase mbed TLS max content length parameter in
order to process it correctly. This also implies an increase in heap
usage, so increase the heap size as well.
Signed-off-by: Robert Lubos <robert.lubos@nordicsemi.no>