chore: remove java 7 units check (#926)

This PR was generated using Autosynth. 🌈

Synth log will be available here:
https://source.cloud.google.com/results/invocations/f82e3ee2-2f75-4393-ba94-04566b86ebe9/targets

- [ ] To automatically regenerate this PR, check this box. (May take up to 24 hours.)

Source-Link: googleapis/synthtool@1a2878d

.github/workflows/ci.yaml

@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        java: [7, 8, 11]
+        java: [8, 11]
     steps:
     - uses: actions/checkout@v2
     - uses: actions/setup-java@v1

synth.metadata

@@ -4,7 +4,7 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-bigtable.git",
-        "sha": "7d5108ec2f2803bf1a517658a3c5471e372c50a7"
+        "sha": "1afeb4274bae0c5f754720155cb84adbfda74c93"
       }
     },
     {
@@ -19,7 +19,7 @@
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "5d3c52f5db664eee9026db76b5bcb466f3a09ca9"
+        "sha": "1a2878d6909dd10ca4e3c1b5943d6622e996054e"
       }
     }
   ],