[Security Solution] Adjust Cypress buildkite job config (#159000)

## Summary

Due to #158236 there is no need to
run Security Solution Cypress tests on 15 buildkite agents anymore

.buildkite/pipelines/pull_request/security_solution.yml

@@ -4,8 +4,8 @@ steps:
     agents:
       queue: n2-4-spot
     depends_on: build
-    timeout_in_minutes: 120
-    parallelism: 15
+    timeout_in_minutes: 60
+    parallelism: 7
     retry:
       automatic:
         - exit_status: '-1'

x-pack/plugins/security_solution/package.json

@@ -11,7 +11,7 @@
     "cypress:open": "TZ=UTC node ./scripts/start_cypress_parallel open --spec './cypress/e2e/**/*.cy.ts' --config-file ./cypress/cypress.config.ts --ftr-config-file ../../../../../../x-pack/test/security_solution_cypress/cli_config",
     "cypress:open:ccs": "yarn cypress:open --config specPattern=./cypress/ccs_e2e/**/*.cy.ts",
     "cypress:open:upgrade": "yarn cypress:open --config specPattern=./cypress/upgrade_e2e/**/*.cy.ts",
-    "cypress:run": "yarn cypress:run:reporter --browser chrome --spec './cypress/e2e/**/*.cy.ts'; status=$?; yarn junit:merge && exit $status",
+    "cypress:run": "yarn cypress:run:reporter --browser chrome --spec './cypress/e2e/{,!(investigations)/**/}*.cy.ts'; status=$?; yarn junit:merge && exit $status",
     "cypress:run:cases": "yarn cypress:run:reporter --browser chrome --spec './cypress/e2e/cases/*.cy.ts' --ftr-config-file ../../../../../../x-pack/test/security_solution_cypress/cases_cli_config; status=$?; yarn junit:merge && exit $status",
     "cypress:run:firefox": "yarn cypress:run:reporter --browser firefox --spec './cypress/e2e/**/*.cy.ts'; status=$?; yarn junit:merge && exit $status",
     "cypress:run:reporter": "TZ=UTC node ./scripts/start_cypress_parallel run --config-file ./cypress/cypress_ci.config.ts --ftr-config-file ../../../../../../x-pack/test/security_solution_cypress/cli_config --reporter ../../../node_modules/cypress-multi-reporters --reporter-options configFile=./cypress/reporter_config.json",