Remove POSTGRES_HOST_AUTH_METHOD from examples and add passwords

[BretFisher]

remove POSTGRES_HOST_AUTH_METHOD from examples and add passwords to make examples more realistic.

Also in C2, C3, and C4

C1 examples, mostly Swarm:

❯ ag POSTGRES_HOST_AUTH_METHOD
swarm-stack-4/voting-app-placement.yml
18:            - POSTGRES_HOST_AUTH_METHOD=trust

swarm-stack-4/answer/voting-app-placement.yml
22:            - POSTGRES_HOST_AUTH_METHOD=trust

swarm-stack-5/example-voting-app-stack.yml
10:            - POSTGRES_HOST_AUTH_METHOD=trust

swarm-app-1/answer/answer.sh
11:docker service create --name db --network backend -e POSTGRES_HOST_AUTH_METHOD=trust --mount type=volume,source=db-data,target=/var/lib/postgresql/data postgres:9.4

swarm-app-1/README.md
45:  - remember set env for password-less connections -e POSTGRES_HOST_AUTH_METHOD=trust

swarm-stack-6/example-voting-app-stack.yml
14:            - POSTGRES_HOST_AUTH_METHOD=trust

swarm-stack-1/example-voting-app-stack.yml
22:      - POSTGRES_HOST_AUTH_METHOD=trust

example-voting-app/answer/example-voting-app-stack.yml
40:      - POSTGRES_HOST_AUTH_METHOD=trust

example-voting-app/example-voting-app-stack.yml
14:      - POSTGRES_HOST_AUTH_METHOD=trust