fix: delete env var after test if it was not set (#774)
fix: delete env var after test if it was not set (#774)

* fix: delete env var after test if it was not set

* fix: wrap tests in suite

Co-authored-by: Benjamin E. Coe <69440dae14aaa9fe2429b324bfce03449d09e1db@google.com>

googleapis/nodejs-spanner,googleapis/nodejs-spanner,googleapis/nodejs-spanner,googleapis/nodejs-spanner