ETL-376: remove status from get pipeline response

[PabloPardoGarcia]

• Remove fetching status from GET pipeline response
• Fetch status from /health endpoint instead
• Unify mocking strategy

[github-actions]

Test Coverage Report

File	Stmts	Miss	Cover	Missing
etl
__init__.py	5	0	100%
api_client.py	64	5	92%	70–73, 123
client.py	39	4	89%	59–61, 141
dlq.py	33	2	93%	45, 70
errors.py	27	0	100%
pipeline.py	141	7	95%	326–329, 342, 397–398
tracking.py	26	0	100%
etl/models
__init__.py	7	0	100%
base.py	10	1	90%	10
config.py	34	8	76%	37, 40–41, 43–45, 47–48
data_types.py	57	0	100%
join.py	45	1	97%	44
pipeline.py	115	9	92%	70, 75, 79, 95, 114, 136, 155, 168, 176
sink.py	39	0	100%
source.py	118	5	95%	57, 70, 104, 109, 143
TOTAL	760	42	94%