ci: remove ejson (#30653)

.buildkite/env/.gitignore

@@ -1 +0,0 @@
-/secrets_unencrypted.ejson

.buildkite/env/README.md

@@ -1,31 +0,0 @@
-
-[ejson](https://github.com/Shopify/ejson) and
-[ejson2env](https://github.com/Shopify/ejson2env) are used to manage access
-tokens and other secrets required for CI.
-
-#### Setup
-```bash
-$ sudo gem install ejson ejson2env
-```
-
-then obtain the necessary keypair and place it in `/opt/ejson/keys/`.
-
-#### Usage
-Run the following command to decrypt the secrets into the environment:
-```bash
-eval $(ejson2env secrets.ejson)
-```
-
-#### Managing secrets.ejson
-To decrypt `secrets.ejson` for modification, run:
-```bash
-$ ejson decrypt secrets.ejson -o secrets_unencrypted.ejson
-```
-
-Edit, then run the following to re-encrypt the file **BEFORE COMMITING YOUR
-CHANGES**:
-```bash
-$ ejson encrypt secrets_unencrypted.ejson
-$ mv secrets_unencrypted.ejson secrets.ejson
-```
-

.buildkite/env/secrets.ejson

@@ -1,7 +0,0 @@
-{
-    "_public_key": "ae29f4f7ad2fc92de70d470e411c8426d5d48db8817c9e3dae574b122192335f",
-    "_comment": "These credentials are encrypted and pose no risk",
-    "environment": {
-      "CODECOV_TOKEN": "EJ[1:KToenD1Sr3w82lHGxz1n+j3hwNlLk/1pYrjZHlvY6kE=:hN1Q25omtJ+4yYVn+qzIsPLKT3O6J9XN:DMLNLXi/pkWgvwF6gNIcNF222sgsRR9LnwLZYj0P0wGj7q6w8YQnd1Rskj+sRroI/z5pQg==]"
-    }
-}

.buildkite/hooks/pre-command

@@ -1,8 +1,6 @@
 #!/usr/bin/env bash
 set -e
 
-# eval "$(ejson2env .buildkite/env/secrets.ejson)"
-
 # Ensure the pattern "+++ ..." never occurs when |set -x| is set, as buildkite
 # interprets this as the start of a log group.
 # Ref: https://buildkite.com/docs/pipelines/managing-log-output