testing: various cleanups [(#3877)](GoogleCloudPlatform/python-docs-s…

…amples#3877)

* testing: various cleanups

* [iap]: only run iap tests on Kokoro
* [vision/automl]: use temporary directory for temporary files
* [appengine/flexible/scipy]: use temporary directory
* [bigtable/snippets/reads]: update pytest snapshot
* [texttospeech/cloud-client]: added output.mp3 to .gitignore
* [iot/api-client/gcs_file_to_device]: use temporary directory
* [iot/api-client/mqtt_example]: use temporary directory
* [logging/cloud-client]: use uuid and add backoff

* use project directory with Trampoline V1

samples/snippets/reads/snapshots/snap_reads_test.py

@@ -7,14 +7,6 @@
 
 snapshots = Snapshot()
 
-snapshots['test_read_simple 1'] = '''Reading data for phone#4c410523#20190501:
-Column Family stats_summary
-\tconnected_cell: \x00\x00\x00\x00\x00\x00\x00\x01 @2019-05-01 00:00:00+00:00
-\tconnected_wifi: \x00\x00\x00\x00\x00\x00\x00\x01 @2019-05-01 00:00:00+00:00
-\tos_build: PQ2A.190405.003 @2019-05-01 00:00:00+00:00
-
-'''
-
 snapshots['test_read_row_partial 1'] = '''Reading data for phone#4c410523#20190501:
 Column Family stats_summary
 \tos_build: PQ2A.190405.003 @2019-05-01 00:00:00+00:00
@@ -140,3 +132,11 @@
 \tos_build: PQ2A.190406.000 @2019-05-01 00:00:00+00:00
 
 '''
+
+snapshots['test_read_row 1'] = '''Reading data for phone#4c410523#20190501:
+Column Family stats_summary
+\tconnected_cell: \x00\x00\x00\x00\x00\x00\x00\x01 @2019-05-01 00:00:00+00:00
+\tconnected_wifi: \x00\x00\x00\x00\x00\x00\x00\x01 @2019-05-01 00:00:00+00:00
+\tos_build: PQ2A.190405.003 @2019-05-01 00:00:00+00:00
+
+'''