Use socket timeout value for tcp timeout if available

Make the inet subsystem initialize the tcp timeout value with the env.
variable LTTNG_NETWORK_SOCKET_TIMEOUT if available.

Signed-off-by: David Goulet <dgoulet@efficios.com>
Fix: remove health test from fast regression

Signed-off-by: David Goulet <dgoulet@efficios.com>
Tests: fix health tests to use custom socket timeout

Signed-off-by: David Goulet <dgoulet@efficios.com>
Tests: change buffers UID test to PID

Signed-off-by: David Goulet <dgoulet@efficios.com>
Fix: missing check for metadata data pending

Signed-off-by: David Goulet <dgoulet@efficios.com>