refactor: rename pod to deployment

[jacobowitz]

Closes #4209

This PR renames Pod to Deployment and Pea to Pod.

[github-actions]

Latency summary

Current PR yields:

• 🐢🐢 index QPS at 30, delta to last 2 avg.: -97%
• 🐎🐎🐎🐎 query QPS at 36, delta to last 2 avg.: +23%
• 🐎🐎🐎🐎 avg flow time within 2.1057 seconds, delta to last 2 avg.: +75%
• 🐎🐎🐎🐎 import jina within 0.4518 seconds, delta to last 2 avg.: +20%

Breakdown

Version	Index QPS	Query QPS	Avg Flow Time (s)	Import Time (s)
current	30	36	2.1057	0.4518
2.6.4	1303	26	1.0647	0.411
2.6.3	1521	32	1.3297	0.3404

Backed by latency-tracking. Further commits will update this comment.

[codecov]

Codecov Report

Merging #4230 (6192888) into master (ecaae24) will increase coverage by 0.97%.
The diff coverage is 86.98%.

@@            Coverage Diff             @@
##           master    #4230      +/-   ##
==========================================
+ Coverage   86.21%   87.19%   +0.97%     
==========================================
  Files         114      113       -1     
  Lines        8286     8254      -32     
==========================================
+ Hits         7144     7197      +53     
+ Misses       1142     1057      -85     

Flag	Coverage Δ
daemon	42.23% <57.39%> (-0.18%)	⬇️
jina	86.93% <86.88%> (+8.10%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
jina/__init__.py	69.31% <ø> (ø)
jina/checker.py	96.29% <ø> (ø)
jina/clients/mixin.py	90.47% <ø> (ø)
jina/helper.py	81.87% <0.00%> (+0.83%)	⬆️
jina/jaml/parsers/executor/legacy.py	91.17% <ø> (ø)
jina/orchestrate/deployments/config/helper.py	96.15% <ø> (ø)
...rate/deployments/config/k8slib/kubernetes_tools.py	100.00% <ø> (ø)
jina/orchestrate/pods/container_helper.py	73.80% <ø> (ø)
jina/parsers/deprecated.py	83.33% <ø> (ø)
jina/parsers/helper.py	45.18% <ø> (ø)
... and 61 more

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[github-actions]

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