fix(windows): use %ProgramFiles% and %ProgramData% for default configuration variables

[tsomerve]

Summary

Fix Windows zip installation on hosts where %ProgramFiles% or %ProgramData% are
remapped to a non-system drive (e.g. E: on FedRAMP-restricted environments). Secondary
services — fluent-bit/logging and nri-winservices — fail to start because the agent
resolves their paths to C: instead of the actual installation drive.

Root cause

Two independent bugs share the same class of mistake: using a hardcoded drive letter
instead of the appropriate Windows environment variable.

Bug 1 — pkg/config/config_windows.go

defaultAgentDir is built by concatenating %SystemDrive% with the string
"Program Files\New Relic\newrelic-infra". When %ProgramFiles% is remapped to E:
but %SystemDrive% is still C:, every path derived from defaultAgentDir resolves to
C: — including the fluent-bit exe path, safe_bin_dir, and config_dir.

// before
sysDrive := os.Getenv("SystemDrive") + string(filepath.Separator)
defaultAgentDir = filepath.Join(sysDrive, installationSubdir)

// after
defaultAgentDir = filepath.Join(os.Getenv("ProgramFiles"), "New Relic", "newrelic-infra")

Bug 2 — cmd/newrelic-infra/initialize/initialize_windows.go

agentTemporaryFolder is hardcoded to C:\ProgramData\New Relic\newrelic-infra\tmp.
emptyTemporaryFolder() only creates the temp directory when
cfg.AgentTempDir == agentTemporaryFolder. When %ProgramData% is remapped to E:,
cfg.AgentTempDir resolves to E:\ProgramData\... and the condition is always false —
the temp directory is never created on first run, blocking fluent-bit config generation.

// before (const)
agentTemporaryFolder = "C:\\ProgramData\\New Relic\\newrelic-infra\\tmp"

// after (var, derived at startup)
var agentTemporaryFolder = filepath.Join(os.Getenv("ProgramData"), "New Relic", "newrelic-infra", "tmp")

Files changed

File	Change
pkg/config/config_windows.go	Use %ProgramFiles% for defaultAgentDir; remove unused installationSubdir const
cmd/newrelic-infra/initialize/initialize_windows.go	Replace hardcoded C:\ProgramData constant with %ProgramData% env var; add path/filepath import

Testing

Reproduced on a Windows Server 2019 Azure VM with %ProgramFiles% and %ProgramData%
remapped to E: and the agent installed via zip. Confirmed:

• Before fix: agent starts, fluent-bit reports "exe not found" at
  C:\Program Files\...\logging\fluent-bit.exe (wrong drive)
• After fix (simulated via config): fluent-bit found at
  E:\Program Files\...\logging\fluent-bit.exe, progresses to full initialization

Startup log showing the bug (agent_dir on C: despite agent installed on E:):

agent_dir="C:\\Program Files\\New Relic\\newrelic-infra"
Fluent Bit exe not found. fbExePath="C:\\Program Files\\New Relic\\newrelic-infra\\newrelic-integrations\\logging\\fluent-bit.exe"

Workaround for existing customers

Until this fix ships, customers can set all three in newrelic-infra.yml (note:
double-escaped backslashes are required in YAML double-quoted strings):

agent_dir:    "E:\\Program Files\\New Relic\\newrelic-infra"
config_dir:   "E:\\Program Files\\New Relic\\newrelic-infra"
safe_bin_dir: "E:\\Program Files\\New Relic\\newrelic-infra"

This does not work around Bug 2. The temp directory must also be pre-created manually:

New-Item -ItemType Directory -Force "E:\ProgramData\New Relic\newrelic-infra\tmp"