tests: switch from lazy_static to once_cell

Once_cell does not require using macro and is slated to become part of
Rust std at some point.

Signed-off-by: Wei Liu <liuwe@microsoft.com>

Cargo.lock

@@ -165,10 +165,10 @@ dependencies = [
  "epoll",
  "event_monitor",
  "hypervisor",
- "lazy_static",
  "libc",
  "log",
  "net_util",
+ "once_cell",
  "option_parser",
  "seccompiler",
  "serde_json",
@@ -1038,8 +1038,8 @@ version = "0.1.0"
 dependencies = [
  "dirs",
  "epoll",
- "lazy_static",
  "libc",
+ "once_cell",
  "ssh2",
  "vmm-sys-util",
  "wait-timeout",