Improve robustness of Pager results

[bcantoni]

In some cases, Tableau Server might have a different between the advertised total number of object and the actual number returned via the Pager.

This change adds one more check to prevent errors from happening in these situations.

Fixes #1304

[github-actions]

Coverage Report

File	Stmts	Miss	Cover	Missing
tableauserverclient
__init__.py	4	0	100%
_version.py	279	163	163	42%
config.py	5	0	100%
datetime_helpers.py	25	1	1	96%
exponential_backoff.py	20	0	100%
filesys_helpers.py	31	0	100%
namespace.py	26	3	3	88%
tableauserverclient/helpers
__init__.py	1	0	100%
headers.py	13	8	8	38%
logging.py	2	0	100%
strings.py	27	1	1	96%
tableauserverclient/models
__init__.py	37	0	100%
column_item.py	55	32	32	42%
connection_credentials.py	35	11	11	69%
connection_item.py	77	10	10	87%
custom_view_item.py	119	9	9	92%
data_acceleration_report_item.py	54	1	1	98%
data_alert_item.py	159	3	3	98%
data_freshness_policy_item.py	156	15	15	90%
database_item.py	203	34	34	83%
datasource_item.py	240	11	11	95%
dqw_item.py	104	5	5	95%
exceptions.py	4	0	100%
favorites_item.py	57	8	8	86%
fileupload_item.py	19	0	100%
flow_item.py	149	10	10	93%
flow_run_item.py	72	0	100%
group_item.py	81	3	3	96%
interval_item.py	183	34	34	81%
job_item.py	177	12	12	93%
metric_item.py	130	12	12	91%
pagination_item.py	34	0	100%
permissions_item.py	75	7	7	91%
project_item.py	144	31	31	78%
property_decorators.py	99	18	18	82%
reference_item.py	19	0	100%
revision_item.py	60	3	3	95%
schedule_item.py	206	6	6	97%
server_info_item.py	39	5	5	87%
site_item.py	610	12	12	98%
subscription_item.py	103	3	3	97%
table_item.py	118	18	18	85%
tableau_auth.py	71	26	26	63%
tableau_types.py	23	1	1	96%
tag_item.py	16	0	100%
target.py	6	0	100%
task_item.py	57	2	2	96%
user_item.py	277	17	17	94%
view_item.py	178	15	15	92%
webhook_item.py	66	0	100%
workbook_item.py	275	16	16	94%
tableauserverclient/server
__init__.py	8	0	100%
exceptions.py	4	0	100%
filter.py	21	1	1	95%
pager.py	37	4	4	89%
query.py	109	21	21	81%
request_factory.py	966	138	138	86%
request_options.py	267	4	4	99%
server.py	164	17	17	90%
sort.py	6	0	100%
tableauserverclient/server/endpoint
__init__.py	28	0	100%
auth_endpoint.py	76	12	12	84%
custom_views_endpoint.py	68	2	2	97%
data_acceleration_report_endpoint.py	21	0	100%
data_alert_endpoint.py	97	25	25	74%
databases_endpoint.py	103	33	33	68%
datasources_endpoint.py	308	41	41	87%
default_permissions_endpoint.py	46	5	5	89%
dqw_endpoint.py	43	16	16	63%
endpoint.py	167	16	16	90%
exceptions.py	60	6	6	90%
favorites_endpoint.py	95	22	22	77%
fileuploads_endpoint.py	51	0	100%
flow_runs_endpoint.py	63	10	10	84%
flow_task_endpoint.py	23	3	3	87%
flows_endpoint.py	217	60	60	72%
groups_endpoint.py	107	11	11	90%
jobs_endpoint.py	58	8	8	86%
metadata_endpoint.py	88	14	14	84%
metrics_endpoint.py	58	8	8	86%
permissions_endpoint.py	46	5	5	89%
projects_endpoint.py	127	22	22	83%
resource_tagger.py	40	10	10	75%
schedules_endpoint.py	100	11	11	89%
server_info_endpoint.py	35	10	10	71%
sites_endpoint.py	126	28	28	78%
subscriptions_endpoint.py	58	15	15	74%
tables_endpoint.py	102	39	39	62%
tasks_endpoint.py	65	7	7	89%
users_endpoint.py	127	15	15	88%
views_endpoint.py	124	10	10	92%
webhooks_endpoint.py	57	11	11	81%
workbooks_endpoint.py	335	42	42	87%
TOTAL	9721	1268	87%

[bcantoni]

It took a little work but I found an internal QA server that exhibited the reported bug with paginating through subscriptions with TSC v0.30 (and also v0.29). Testing with this branch worked correctly.